Exam 2 (Chapters 4-6) Flashcards
A sample chosen such that individuals are chosen with the specific probability
Probability sample
A sample chosen such that the probability of an individual being chosen cannot be determined
Convenience or purposive sample
A sample chosen randomly from the population such that each individual has an equal chance of being selected
Simple random sample
A sample chosen randomly from clusters identified in the population
Cluster sample
A sample chosen from the population such that the proportion of individuals with a particular characteristic is equivalent in the population and sample
Stratified random sample
A sample chosen from the population such that available individuals are chosen based on who volunteers to participate
Volunteer sample
A sample chosen from the population such that available individuals are chosen with equivalent proportions of individuals for a specific characteristic in the population and sample
Quota sample
The spread of scores in a distribution
Variability
The distribution of all possible sample means for all possible samples of a particular size from a population
Distribution of sample means
A sample chosen from the population by recruiting on the Internet
Internet sample
What is the advantage to simple random sample?
It reduces sampling error by choosing from all members of the population to best represent the population
What are some disadvantages to simple random sample
It is difficult to ensure that each member of a large population can be chosen in a sample
Students are chosen randomly from a list of all students at a University
This is an example of what sample technique
Simple random sample
What are the advantages of a cluster sample
It makes it easier to choose members randomly from small clusters to better represent the population
What are the disadvantages to cluster sampling
It can ignore segments of the population that are not in the clusters chosen for the sample
Doctors who work at hospitals are chosen for example by identifying all hospitals in different areas of the United States and then randomly choosing 10 hospitals in each area of the United States to sample from
This is an example of what type of sampling technique
Cluster sample
What are the advantages to stratified random sampling
It reduces bias due to an Identified characteristic of the population by equating proportions in the sample and the population for that characteristic to better represent the population
What are some of the disadvantages to stratified random sampling
It is similar to simple random sampling which can be difficult to ensure equal probability of being chosen from a large population
Registered voters are randomly selected from lists of democrats and republicans to equal the proportion of registered democrats and republicans in the United States
Is an example of which sampling technique
Stratified random sampling
What are some of the advantages to convenience sampling
It is easier to obtain than probability samples
What are the disadvantages to convenience sampling
It may not represent the population properly due to selection bias because random sampling is not used
The sample is chosen from students who volunteer to complete an extra credit assignment in their psychology course
This is an example of what sampling technique
Convenience sampling
Convenient samples can also be known as which type of samples
Volunteer sample or quota sample
True or False
The larger the difference between scores in the sample data, the less reliable it is as an estimate of the population data
True
true or false
Data from one sample will not tell us everything we need to know about the research questions we are asking with our study because, by chance, we may not have collected data from our sample that does a good job of representing the population data.
True
What are 2 things that you need to keep in mind when trying to recruit participants
How you will contact your participants and their compensation
For each of the following study descriptions, describe how you would select a sample from the population using one of the techniques describe in this chapter:
A. You want to know how adults in your country feel about the issue of immigration.
B. You want to know how anxious college seniors are about their job prospects.
C. You want to learn about how people remember information based on their mood.
A. Since a simple random sample would be too difficult to take, I would try to take a cluster sample. It would be important to get people from across the country to weigh in. That is, people in urban and rural settings, or maybe more to the point, people living in areas with a high number of immigrants and people living in areas with a low number of immigrants.
B. You could conduct a simple random sample of seniors at your university or college or you could do this for a number of universities/colleges of different types
C. Again, a simple random sample of “people” is too broad, even if it’s narrowed to adults in this country. A type of convenience sample, like a volunteer sample, might not be a bad idea. You’re probably looking for a lot of people and not too worried about demographics.
The distribution of a sample means shows ______.
A. The frequency of scores in a sample
B. The frequency of means from all samples from a population
C. The sampling error that exists in a sample
D. The sampling error that exists in a population
B. The frequency of means from all samples from a population
True or false
Sampling error will only be present in convenience samples, not in probability samples.
False
Our measure of sampling errors affected by _________.
A. Sample size
B. Population size
C. Variability in the data
D. Both A and B
E. Both A and C
E.
Probability plays a role in ______.
A. Selecting a representative sample
B. Estimating sampling error
C. Determining the mean of our sample
D. All of the above
A
True or false
A probability sample typically has less sampling error than a convenient sample.
True
In a simple random sample, _______.
A. Is sample matches the proportions in the population on some characteristic
B. Each individual in the population has an equal chance of being selected
C. Individuals are selected at random from preexisting groups in the population
B
In what ways are probability samples preferable to convenience samples
Probability samples are typically better representatives of the population they are drawn from because the probability of an individual being chosen is determined ahead of time and controlled through random sampling.
Despite the superiority of probability samples, why do many psychological studies use convenience samples?
Many studies use convenience samples because it can be difficult to identify all the members of large populations to randomly select them.
Suppose you were conducting a survey study to learn about drinking behaviors for the population of students at your school with a quota sample. In your sample you want to be sure that you represent the population according to year in school and gender. Describe how you might choose your sample for this study and how your survey would be administered.
There are several ways to do this, but the key is to use a convenience sample of students at the school in the same proportions as they exist at the school as a population based on years in school and gender. These proportions will need to be known before the sample is selected. You will also need a recruitment technique (Internet with e-mail contact, surveys mailed to campus address, etc.) to describe how to administer your survey.
What are some advantages of collecting samples by using the Internet?
Internet samples tend to be more diverse than other samples; they can be collected using fewer resources and in a shorter period of time.
In a _______ sample, individuals are chosen at random from the population but are chosen in proportions equivalent to proportions that exist in the population.
Example 90% right handed, 10% left handed
A. Simple random
B. Haphazard
C. Quota
D. Stratified random
D
In a ______ sample, individuals who volunteer from the population or chosen for the sample
A. Simple random
B. Convenience
C. Quota
D. Stratified random
B
Sampling error is _______.
A. A type of sampling technique
B. The difference and observations between the population and the sample
C. Is an error introduced into a study by the researchers bias
D. None of the above
B
The ______ is the group of individuals a researcher wants to learn about, whereas a ______ is the group of individuals who serves as subjects in a study
Population; Sample
In a ______ sample, all members of the population have an equal chance of being selected
Simple random
The difference in scores that occurs when we test a sample drawn out of the population is ______.
A. sampling error
B. Stratified Error
C. Cluster Error
D. Independent Error
A. Sampling error
The sampling technique that involves choosing individuals from the population at random where each individual has an equal chance of being selected is ______.
A. simple random sample
B. Quota sample
C. volunteer sample
stratified random sample
A. Simple random sample
A quota sample example might be described as ______.
Choose one
people who respond to a mailed survey make up the sample
all students who sign up for a study make up the sample
60% of the population is left-handed, so 60% of the participants chosen are also left-handed
participants are selected from a local preschool class to represent preschoolers who live in the area
C. 60% of the population is left-handed, so 60% of the participants chosen are also left-handed
Individuals are selected at random for a study from a list of members of Girl Scout troops to represent the population of girls aged 8–13. This sampling is ______ sampling.
Choose one
simple random
stratified random
haphazard/volunteer
cluster
D. Cluster
Convenience samples will likely increase the amount of sampling error in the study, lowering its ______ validity by making a test of the hypotheses less accurate.
Choose one
external
sample
haphazard
internal
D. Internal
Convenience samples are also called ______.
Choose one
volunteer samples
haphazard samples
cluster samples
purposive samples
D. Purposive samples
Experiments that require ______ of stimuli can be reproduced for presentation on the Internet to individual participants.
Choose one
systematic presentation
double-blind protocol
repeated measures
random presentation
A. Systemic presentation
In a simple random sample, if a population has 100 individuals, the chance of any one individual being selected for the sample is ______.
Choose one
1 in 100
50 in 100
4 in 100
10 in 100
A. 1 in 100
It is important to use a ______ sample when sampling error is likely to be large.
Choose one
convenience
haphazard
volunteer
probability
D. Probability
______ require access in some way to the entire population to select individuals according to a predetermined probability value.
Choose one
Convenience samples
Haphazard samples
Volunteer samples
Probability samples
D. Probability samples
Concepts of probability are also used to collect data from a sample to learn about a population. This knowledge can be used to conduct research on behavior and test hypothesis using the data collected
Collecting data using probability
Any possible result of an experiment, action, or event
Outcome
We can determine the probability of any result in our data by doing what
Considering the total number of possible outcomes and calculating the proportion of those outcomes that correspond with our result of interest
What does it mean when we consider the likelihood of obtaining the sample mean we got for our sample, given what we know about the population we want to learn about
Finding a sample mean
What is the application of sampling to research studies
To test hypothesis for research studies, researchers must find the probability of a behavior of interest, occurring in the sample
What restrictions are imposed when using nominal or ordinal scale of measurement
The response choices on those scales will determine the possible measurement outcomes from an individual
What restrictions Are imposed when using interval scale As the scale of measurement
Rating scales typically restrict the responses to whole numbers between 2 values, making the possible outcomes one of those values.
What restrictions are imposed by using the ratio scale of measurement
Constrained by a range at the bottom end but can be broken down into smaller and smaller increments, often a large number of possible outcomes.
What is the dartboard analogy
You can consider the entire dartword the population of interest, each location represents a score from someone in that population, the individuals in the sample are the darts
The difference between the population means score and the means score of your sample
Is sampling error
To reduce sampling error as much as possible, we must use a good sampling technique to choose the individuals from the population of our sample. This means we are ______ _______.
Reducing error
What are the 2 steps that are very important to getting a sample
- Select individuals from the population for the sample
- Observe the behaviors you are interested in from the individuals in the sample
Researchers attempt to balance the desire to reduce sampling error and select a representative sample within the practical limits of selecting individuals from very large populations. This balance plays out in the choice between _______ and _______
Probability samples
Convenience/Purposive samples
What are the advantages of probability samples
Probability samples are more likely to be representative of the population
What are the different types of probability samples
- Simple random sample
- Stratified random sample
- Cluster sample
What are the advantages to convenience or purposive sample
Much easier to select and are often used in cases where researchers want to learn about a very large population
What are the advantages and disadvantages to simple random sample
Reduces sampling error but it is difficult to ensure that each member of a large population can be chosen in a sample
What are the advantages and disadvantages to cluster sample
Easier to choose members randomly from smaller clusters but other segments are ignored completely
What are the advantages and disadvantages to stratified random sample
Reduces bias due to an identified characteristic but it can be difficult to ensure equal probability of being chosen from a large population
What are the advantages and disadvantages to convenience sampling
- Ease: Instead of randomly sampling individuals from the population convenient samples rely on samples that are convenient to obtain such as from a University subject pool or from users of the Amazon website MTurk
- Low internal validity: Can sacrifice some internal validity due to an increase in sampling error
How do you choose a valid sample
A sample size should be big enough to reduce sampling error but small enough for the researcher to test the sample in his or her study. A valid sample will reduce the error in the data and give a better estimate of the actual population average
What is the concept of variability
The spread of scores in a distribution
What affects the estimation of your sample error?
Use both the sample size and the sample variability
The distribution of all possible sample means for all possible samples of a particular size from a population is called the….
Distribution of sample means
What are the advantages of using the Internet to recruit participants as a sample
Demographically diverse, fewer opportunities for bias, and fewer constraints
What are the disadvantages to using the Internet to sample
It’s difficult to control participants
The degree to which the results of a study apply to individuals and realistic behaviors outside the study
External validity
The degree to which a study provides causal information about behavior
Internal validity
A data collection technique involving non invasive observation of individuals in their natural environment
Naturalistic observation
A measure of the degree to which different observers rate behaviors in similar ways
Interobserver or interrator reliability
A research study that uses the survey observational technique to measure behavior
Survey research
Participants responses to survey questions according to the response options provided by the researcher
Closed ended response scale
This participants respond to survey questions in any manner they feel appropriate for the question
Open ended response scale
Non numerical participant responses
qualitative
Numerical data is
Is quantitative
A data collection technique that involves direct questioning of individuals about their behaviors and attitudes
Interviews
Data collection technique where control is exerted over the conditions under which the behavior is observed
Systemic observation
Data collection technique that involves analysis of pre existing data
Archival data
An archival data collection technique that involves analysis of the content of an individual spoken or written record
Content analysis
A research design that involves intensive study of particular individuals and their behaviors.
Case study
An experiment conducted with one or a few participants to better understand the behavior of those individuals
Small-n design
A type of research design that examines the relationships between multiple dependent variables without manipulating any of the variables
Correlation study
The dependent variable in a correlation study that is used to predict the score on another variable
Predictor variable
The dependent variable in a correlation study that is being predicted by the predictor variable
Outcome variable
Relationship between variables characterized by an increase in one variable that occurs with an increase in the other variable
Positive relationship
Relationship between variables characterized by an increase in one variable that occurs with a decrease in the other variable
Negative relationship
A graph showing the relationship between 2 dependent variables for a group of individuals
Scatter plot
The presence of extraneous factors in a study that affects the dependent variable and can decrease the internal validity of the study
3rd variable problem
A type of research design that involves manipulation of an independent variable, Allowing control of extrenuous variables that could affect the results
Experiment
A variable in an experiment that is manipulated by the researcher such that the levels of the variable change across or within subjects in the experiment
Independent variable
Different situations or conditions that participants experience in an experiment because of the manipulation of the independent variable
Levels of the independent variable
The group of participants in an experiment that experienced the treatment level of the independent variable
Experimental group
The group of participants in an experiment that do not experience the treatment level of the independent variable
Control group
An extra factor present in a study that may affect the results
Confounding variable
A sugar pill given to the control group and a drug study to allow all groups to believe that they are receiving treatment
Placebo
A type of research design where a comparison is made, as in an experiment, but no random assignment of participants to groups occurs
Quasi-experiment
Participants are randomly assigned to levels of the independent variable in an experiment to control for individual differences as an extraneous variable. This process is called..
Random assignment
Quasi experiment where subjects are grouped based on a characteristic they already possess (age or gender)
Ex post facto design
A type of experiment design (often a quasi experiment) where behavior is measured both Before & After a treatment or condition is implemented
Pretest-post test design
Suppose you are interested in testing the following hypothesis: “ The Herb ginkgo biloba causes one to have better memory.”
A. What is the best research design to test this hypothesis? Why?
B. Describe the study you would conduct to test this hypothesis.
A. This is a causal hypothesis; thus, an experiment is the best design.
B. A manipulated independent variable that includes random assignment of participants to a ginkgo biloba group and a control group that receives a placebo should be included. Memory should be measured as the dependent variable.
_________ Validity indicates that a study’s results can be generalized to other individuals and real life situations
External
__________ Validity indicates that a study’s results provide casual information about the variables tested
Internal
For each of the following descriptions indicate which data collection technique was used:
Medical records of patients with depression are examined to determine how often these patients attempt suicide based on what type of treatment they received.
archival data
For each of the following descriptions indicate which data collection technique was used:
Participants are asked to perform a task on a computer where they must unscramble sentences as quickly as possible the amount of time it takes to complete the task on each trial is recorded
systematic observation
For each of the following descriptions indicate which data collection technique was used
A series of statements regarding their alcohol consumption behaviors is presented to participants- they are asked to rate their agreement with each statement on a scale from 1 to 5
survey/questionnaire
For each of the following descriptions indicate which data collection technique was used
Students in a college class are observed to record the numbers of times they exhibit behaviors indicating lack of attention to the lecture
naturalistic observation
If a study finds that as self esteem goes up, symptoms of depression decrease, the study has found a _________ relationship
Negative
_____________ Research designs are typically used when a researcher wants to explore the behavior of an individual or group of individuals to better understand unusual or atypical behaviors
Case study
A researcher wants to study factors that cause people to become anxious. She randomly assigns groups of students to 1 of 2 conditions: 1. Performing a timed task with a clock running on the screen while they perform the task or 2. Performing an untimed task while someone watches them complete the task. She compares the accuracy on the task for the two groups. The study used _____________ research design.
A. Case study
B. Correlation
C. Experimental
D. Quasi-experiment
C. Experiment
An instructor of a statistics course is interested in the relationship between how long it takes students to take an exam and their exam score. He times the students on their exam while they take it on a computer and then looks at the relationship between time for the exam and the exams scores for the students. This study used a ___________ research design.
A. Case study
B. Correlation
C. Experimental
D. Quasi-experiment
B. Correlation
You arrive at a study you signed up to participate in. The researchers asked you to write down the time you spent asleep the night before. Then they ask you to perform a task categorizing items into living and non living categories. At the end of the study you are told that the purpose of this study was to see if people who slept 7 hours or more the night before perform the task faster than people who slept less than 7 hours. This study used a ______________ research design.
A. Case study
B. Correlational
C. Experimental
D. Quasi-experiment
D. Quasi-experiment
The calculated average of the scores in a distribution
Mean
The middle score in a distribution, Such that half of the scores are above 1/2 are below that value
Median
The most common score in a distribution
Mode
Representation of a typical score in a distribution
Central tendency
Measurement of the length of time to complete a task
Reaction time
A measure representing the average difference between the scores and the mean of a distribution
Standard deviation
The standard deviation of a distribution squared
Variance
The number of scores that can vary in the calculation of a statistics
Degrees of freedom
Measures with responses as categories that cannot be divided into smaller units
Categorical variables
Graphs of data for categorical variables where the bar height represents the size of the value (mean)
Bar graphs
Measures with numbers scores that can be divided into smaller units
Continuous variables
Graphs of data for continuous variables where each value is graffed as a point and the points are connected to show differences between scores (means)
Line graphs
Ranges of values that the population mean likely falls in with a specific level of certainty
Confidence intervals
A graph showing the relationship between 2 dependent variables for a group of individuals
Scatterplot
Calculate the mean medium and mode. Which measure of central tendency would you choose as the most representative of the dataset? why?
1, 3, 4, 4, 4, 5, 7
Mean: 4, Median: 4, Mode: 4
Each measure of central tendency is the same, so they are all equally representative.
For the following data set calculate the mean, median, and mode. Which measure of central tendency would you choose as the most representative of the dataset? why?
1, 1, 1, 1, 1, 2, 2, 7
Mean: 2, Median: 1, Mode: 1
The mean is most representative. A median might normally be good for a set of scores skewed to one end, but in this case the most common score is the lowest possible score. The mean provides a bit more balance, since the range runs from 1-7.
For the following data set calculate the mean median and mode. Which measure of central tendency would you choose as the most representative of the dataset? why?
1, 2, 3, 2, 2, 5, 7, 7, 7, 2, 7, 2, 7, 7, 2
Mean: 4.2, Median: 3, Mode: 2, 7
The mean, because it balances a set of scores heavy on the low and high ends.
How do the mean, median, and mode compare for symmetrical and skewed distributions?
- The mean is best when the distribution is symmetrical.
- The median is better when one or two outliers skew the distribution.
- The mode is good when there are many scores at the high end and low end.
Which measures of central tendency is most commonly reported?
A. Mean
B. Median
C. Mode
D. None of the above
A. Mean
Which measure of central tendency is most affected by extreme scores?
A. Mean
B. Median
C. Mode
D. None of the above
A. Mean
Which measure of central tendency is most appropriate to report for skewed distribution?
A. Mean
B. Median
C. Mode
D. None of the above
B. Median
Which measure of central tendency is most appropriate for nominal data?
A. Mean
B. Median
C. Mode
D. None of the above
C. Mode
Which measure of central tendency will provide the middle score in a symmetrical distribution?
A. Mean
B. Median
C. Mode
D. None of the above
D. None of the above
The purpose of reporting a measure of central tendency is to indicate the spread of the scores in a distribution
True or false
False
The mean of a distribution is a descriptive statistics
True or false
True
In a positively skewed distribution the mean will be lower than the median.
True or false
False
The mean is the best measure of central tendency to report when there are open ended responses on the measurement scale
True or false
False
For each of the following data sets, which appears to have the highest variability? Explain your answer. And what is the standard deviation for each?
A. 3, 3, 4, 4, 4, 2, 3
B. 1, 1, 1, 1, 1, 2, 2, 7
C. 4, 2, 3, 2, 3, 5, 7, 7, 7, 4, 7, 2, 7, 7, 3
- data set C has the highest variability.
A. SD: .75
B. SD: 2.07
C. SD: 2.13
Which measure of variability is most commonly reported?
A. Standard Deviation
B. Variance
A. Standard Deviation
Degrees of freedom are used in calculating the standard deviation for population.
True or false
False
The variability of scores for a sample will be lower than the variability in the population it represents.
True or false
True
Explain why we need to square the deviations from the mean in our calculation of the standard deviation.
If we did not square the deviations from the mean, the sum of the deviations would be zero. We need a value to work with.
Where should you place tables and figures of data in an APA style research report?
A. Embedded within the results section
B. On a separate page at the beginning of the paper
C. On a separate page at the end of the paper
D. Embedded within the introduction
C. On a separate page at the end of the paper.
Which graph is most appropriate for data with categorical variables?
A. Bar graph
B. Line graph
C. Both A and B
A. Bar graph
Which graph is most appropriate for data with continuous variables?
A. Bar graph
B. Line graph
C. Both A and B
B. Line graph
Whenever you present data in a graph, you should always also include the exact values from the graph in a table.
True or false
False
Creating graphs in SPSS usually requires calculation of descriptive statistics before you begin.
True or false
False
Inferential statistics are typically presented in graphs in a research report.
True or false
False
______ is the average score in a set of data.
Choose one
A. Mean
B. Median
C. Mode
D. Central tendency
A. Mean
Many standardized tests have a known ______.
Choose one
A. population mean
B. distribution
C. sample mean
D. central tendency
A. Population mean
One way to think of the mean of a distribution is as the balancing point of the ______.
Choose one
A. population mean
B. distribution
C. sample mean
D. central tendency
B. Distribution
______ will bias the mean toward the high or low end of the scale, depending on whether they are extremely high or extremely low
Choose one
A. Skew
B. Kurtosis
C. Outlier
D. Plots
C. Outlier
______ is reported less often than the mean as a measure of central tendency.
Choose one
A. Mean
B. Median
C. Mode
D. Central tendency
B. Median
Skewed distributions with extreme scores at the high or low end of the distribution are often better represented by the ______.
Choose one
A. mean
B. median
C. mode
D. central tendency
C. Mode
______ scales, where categories cannot even be ordered from highest to lowest, create another problem for central tendency calculations.
Choose one
A. Nominal
B. Interval
C. Ratio
D. Ordinal
A. Nominal
When the response scale only has two possible values, this type of distribution is a ______ distribution.
Choose one
A. bimodal
B. bimedial
C. binominal
D. biordinal
A. Bimodal
______ is the simplest of the measures of central tendency to calculate.
Choose one
A. Mean
B. Median
C. Mode
D. Central tendency
C. Mode
When there are two common scores that may not fall in the middle of the distribution, we call these ______.
Choose one
A. bimodal
B. bimedial
C. binominal
D. biordinal
A. Bimodal
A specific type of archival data observation technique that involves analysis of what someone has said or written is ______.
Choose one
A. content analysis
B. transcription
C. construct validity
D. historical review
A. Content analysis
When different observers of behavior record the behavior in a similar way, the measure is said to have good ______.
Choose one
A. inter-rater reliability
B. test–retest validity
C. construct validity
D. parsimony
A. Inter-rater reliability
A variable that affects the results of the study but is not a variable of interest in the study, is called a(n) ______variable.
Choose one
A. independent
B. dependent
C. subject
D. confound
D. Confound
A positive relationship means that the values on the variables change in ______ direction at the same time.
Choose one
A. the same
B. the opposite
C. an equal
D. random
A. The same
The causal relationship between the independent and dependent variables will be unclear if ______ are not controlled.
Choose one
A. subject variables
B. independent variables
C. dependent variables
D. confounding variables
D. Confounding variables
The high external validity of naturalistic observations comes with ______.
Choose one
A. low internal validity
B. high internal validity
C. low reliability
D. high reliability
A. Low internal validity
A study with ______ internal validity provides causal information about behavior.
Choose one
A. measurable
B. low
C. high
D. reliable
C. High
One advantage of using interviews is that you can ask about a specific behavior instead of ______.
Choose one
A. waiting for exhibited behavior spontaneously
B. observing the natural occurrence
C. prompting the behavior
D. coding the behavior
A. waiting for exhibited behavior spontaneously
A survey response scale where participants respond to survey questions with options provided by the researcher is a(n) ______ scale
Choose one
A. closed-ended
B. nonverbal
C. open-ended
D. Likert-type
A. Closed-ended
Researchers use ______ of participants to levels of the independent variable in an experiment to control for individual differences as an extraneous variable.
Choose one
A. controlled assignment
B. cluster assignment
C. random assignment
D. blind assignment
C. Random Assignment
What are the 4 steps to creating a histogram graph?
- Construct a frequency distribution in table form.
- Draw bars of equal width for each class interval.
- Identify the class intervals on the X axis using either real limits or interval mid points
- Label the axis and give your histogram a title.
A type of graph that consists of a series of rectangles the heights of which represent frequency or relative frequency
Histogram
Because of the nature of qualitative data, the lines in ______ graph do not touch the spaces are indicative of the discontinuity between the categories
Bar graph
Distributions can be _________, which refers to the piquedness of the distribution (how tall or how flat the distribution is)
Kurtosis
The type of statistics which organize and summarize what we know from a sample
Descriptive statistics
The type of statistics which help us draw conclusions about what is probably happening in a population based on observations made from a sample
Inferential statistics
This information you have about a population is called a ________
Parameter
Information you have about a sample is a _________
Statistic
If there are answerable questions that are asked and investigated. Part of the answer to the question comes from the _________ ___________
Statistical Analysis
In research and statistics one we will focus on _________, and in research and statistics 2 you will focus on __________
Correlation, Experiments
This variable is manipulated by the investigator
Independent
This variable is measured by the investigator
Dependent variable
How can you ensure that you’ll get a good answer to your research question?
- In an experiment, control all variables except for the ones that we are interested in manipulating
- Ask the statistical question
What is a question about the numerical aspect of the observations
Statistical question
The conclusion about the numerical property of the data
Statistical conclusion
What is the conclusion about the subject matter, using this statistical conclusion?
Research conclusion
Your conclusions are only as good as what
- Your ability to control confound variables
- Your ability to conduct statistical analysis
- Your ability to apply the statistical conclusion to the research conclusion
A single summary figure or number that best describes the central location of an entire distribution of observations
Measures of central tendency
What are the 3 types of central tendency that we will discuss
- Mean
- Median
- Mode
What does the symbol (Mo) mean?
Mode
What does the symbol (Mdn) mean?
Median
What does the symbol (fancy m x) mean?
Mean of a population
What does the symbol ( bar over x) mean?
Mean of a sample
What does the symbol (n) mean?
Sample size
What does the symbol (N) mean?
Population size
The 17th score would be written how to represent the value of X?
X17
If you have two sets of data, the second set is noted with ____ instead of X
Y
Greek alphabet sigma means?
Sum
A rectangular distribution has no _____
Mode
A unimodal distribution has ___ mode
1
What is the only central tendency that can be used for nominal data
Mode
What does it mean for the mean median and mode in a perfectly symmetrical, unimodal (normal) distribution?
The mean = the median = the mode
If a distribution is negatively skewed, it is skewed to the left which means what happens to the relationship between mean median and mode
- Lower scores on the left
- Mean > median > mode
If a distribution is positively skewed, it is skewed to the left, which means..
- There are fewer values on the right
- Mean < median < mode
The difference between the lowest score and the highest score and a distribution (spread)
Range = h - l
(h- highest score, l- lowest score)
This shows how much a score differs from the mean
Deviation score
How do you calculate a deviation score
Subtract the mean from the raw scores
(X - X bar)
If the deviation score is positive then it was _______ than the mean
Greater
If the deviation score is negative then the raw score was ______ than the mean
Less
What are some problems with just relying on deviation score
- We cannot use the deviation scores to answer this question. If we sum them, we get 0.
- We cannot simply drop the sign.
- We could square the deviation scores and this would give us all positive numbers which would then sum. Then we could use this number in a meaningful way.
What is an easy way to say “the sum of the square deviations from the mean”?
SSx which stands for “Sum of Squares”
For population variance, we use N in the denominator, but for sample variance we use ______
n-1
Why do we use n -1 for sample variance
- The -1 is a correction
- As the sample gets larger the n-1 correction matters less and less
What do we create by making this -1 correction for the sample variance?
- An unbiased estimation of the population variance.
- Artificially forces the variance to be larger than it would otherwise be.
- Degrees of freedom
Staying organized when calculating variance
- Record each score
- Calculate X bar (mean)
- Calculate the deviation scores (x - x bar; you can check by adding these up should = 0 or be very close)
- Square each of the deviation scores (x - x bar)squared
- Sum of these square deviation scores to get the sum of squares (SSx)
- Divide the SSx by N or n as appropriate
What are the problems with using variance and how do we fix these problems?
Prpblems
1. The number doesn’t usually make a lot of sense in terms of data, it is usually big.
2. We manipulated the deviations to get rid of the problem of the deviation scores adding up to equal 0. We squared them.
Solutions
1. Take the square root! This corrects for that manipulation of squaring the terms, and it will give us a smaller number that will make sense in terms of our data.
2. When we take the square root, we get the standard deviation!
An estimate of average amount by which each score deviates from the mean score
Standard deviation
Research papers usually report the mean and standard deviation. This is because the standard deviation is meaningful when we take the mean into account. In what ways is it meaningful?
- It allows us to understand the distribution in terms that allow us to know how it is behaving in general.
- It can help us detect outliers.
- It can help us understand where the bulk of the data lies.
- It can help us compare scores from different distributions, even when the means and standard deviations are different.
What symbol represents variance?
Sx2
What symbols represents standard deviation?
Sx
