Chapter 1-9 Flashcards
An outlier is a data value that…
…is not consistent with the bulk of the data
Which statistics is not resistant to an outlier in the data?
Mean
Which one of these statistics would be affected by an outlier?
Standard Deviation
Which of these statistics is unaffected (not affected) by outliers? A. Mean B. SD C. Interquartile Range D. Range
C. Interquartile range
…
…
True or False: Outliers cause complications in all statistical analysis
False: outliers do affect such statistics such as means and standard deviation but there are appropriate measures of location and spread
True or false: since outliers cause complications in statistical analyses, they should be discarded before computing summaries such as the mean and the standard deviation
False: they should never be discarded without justification
What is a reasonable action if an outlier was a mistake made in measuring the object?
The value should be corrected if possible or discarded if not possible to correct it
What is a reasonable action if an outlier is the value for the only young subject in a sample where all the other values were older subjects?
The value should be discarded and the results summarised and reported for the older subjects only
Tallies and cross-tabulations are used to summarise which of these variable types? A. Quantitative. B. Mathematical C. Continuous D. Categorical
D. Categorical
Which of these variables is a categorical variable?
A. Number of ear pierces a person has
B. Height of a person
C. Weight of a person
D Opinion about legalisation of marijuana
D.
Which of the following variables is not categorical? A. Age of a person B. Gender of a person C. Choice of test item: true of false D. Martial status of a person
A. Age
Which of the following is not a term used for quantitative variable? A. Measurement variable B. Numerical variable C. Continuous Variable D. Categorical variable
D. Categorical variable
A variable that is not the main concern of the study but may be partially responsible for the observed results is known as…
… the cofounding variable
_______ of only a few thousands, or few hundreds, can give reasonable accurate information about a population of many millions
A representative sample
All of the following are categorical variables except?
A. Gender of a student
B. Colour of a car entering the parking low
C. Number of flowers on an azalea plant
D. The state in which a person lives
C.
Which of the following is not a continuous variable?
A. A persons body temp
B. Number of claims received by an insurance company during one day
C. Weight of two dozen shrimp
D. Height in inches of freshman at a university
B.
An experiment was conducted to compare the mean lengths of time required for the body to absorb two drugs ( A and B ). Ten people were randomly selected and assigned to receive one of the drugs. The length of time In minutes for the drug to reach a specified level In the blood was recorded. What is the explanatory variable in tis study?
The type fo drug
What is the percent of data which lies between the minimum and the upper quartile?
75%
Which of the following would indicate that a dataset is not bell shaped?
A. The range is equally to 6 SD
B. The range is larger than the interquartile range
C. The mean is much smaller than the median
D. There are no outliers
C.
Exam scores in % range from 0 to 100. Suppose an exam was difficult and most of the students scored low with only a few students scoring high. Which would best describe the shape of the distribution?
A. Right - Skewed
B. Left - skewed
Right-skewed
If a diagram moves from high (left) to low (right). What direction is it skewed.
Skewed to the right
When the results of an experiment can be applied to real-world conditions, that experiment is said to have... A. Factorial Validity B. Criterion Validity C. Ecological Validity D. Content Validity
C
A frequency distribution in which high scores are most frequent (i.e bars on the graph are highest on the right hand side) is said to be... A. Negatively skewed B. Leptokurtic C. Positively skewed D. Platykurtic
A
Which of the following is designed to compensate for practice effects
A. A repeated measured design
B. Counterbalancing
D. A control condition
D. Giving participants a break between tasks
B
Variation due to variable that have not been measured is known as: A. unsystematic variation B. Homogenous variance C. Systematic variation D. Residual variance
A
What is the standard deviation?
A. The variance sqaured
B. the degree to which scores cluster at the ends of the distribution
C. A measure of relationship b/w two variables
B
What does a low SD indicate?
the values tend to be close to the mean of the set
What does a high SD indicate?
the values are spread out over a wider range
If a test is valid, what does it mean?
A. The test has internal consistency
B. The test will give consistent results
C. The test measured a useful construct or variable
D. The test measures what it claims to measure
D
A variable that measures the effect that manipulating another variable has it known as: A. Independent variable B. Dependent variable C. Cofounding variable D. Predictor variable
B
If the scores on a test have a mean of 26 and a SD of 4, what is the z-score for a score of 18? 2 11 -2 -1.14
-2
18-26)/(4
How do you calculate the z-score?
(score-mean)/(SD)
A frequency distribution in which there are too many scores at the extremes of the distribution said to be: A. Negatively skewed B. Leptokurtic (steep) C. Positively skewed D. Platykurtic (flat)
Platykurtic (flat)
A café owner wanted to compare how much revenue he gained from lattes across different months of the year. What type of variable is 'month'? A. categorical B. dependent C. interval D. continuous
A
Complete the following sentence: A large standard deviation (relative to the value of the mean itself)…
…indicates that the data points are distant from the mean (i.e. the mean is a poor fit of the data).
Complete the following sentence: A small standard deviation (relative to the value of the mean itself)…
…indicates that data points are close to the mean (i.e. the mean is a good fit of the data).
A frequency distribution in which low scores are most frequent (i.e. bars on the graph are highest on the left hand side) is said to be:
positively (right) skewed
A frequency distribution in which there are too many scores at the extremes of the distribution said to be:
Platykurtic (flat)
At Donald’s Donuts the number of donut holes in a bag can vary. Help Donald find the mode.
12,10,10,10,13,12,11,13,10
10
Roger bowled 7 games last weekend. His scores are: 155, 165, 138, 172, 127, 193, 142. What is the range of Roger’s scores?
66
193-127
Find the mean of the following cell phone usage per month: 445, 516, 618, 575, 288
488.4
Find the median from the list of numbers:
60, 58, 52, 48, 60, 67
59
"Students' scores on a biology test" is an example of which scale of measurement? A. Ratio B. interval C. ordinal D. Nominal
A. ratio
Calender year is an example of what scale of measurement?
interval
“Amount of calories in a small Al Marai Yogurt” is which scale of measurement?
Ratio
Shades of lipstick available in A MAC store, is which scale of measurement?
Nominal
Your age is an example of which scale of measurement?
Ratio
ZIP code is an example of which scale of measurement?
nominal
Arranging the shirt sizes as small, medium and large is an example of which scale of measurement?
ordinal
Pain scale in a doctor’s office is an example of which scale of measurement?
ordinal
blood type is an example of which scale of measurement?
nominal
A(n) _________ is a person or object that is a member of the population being studied.
Individual
The entire group of individuals to be studied is called the population. An individual is a person or object that is a member of the population being studied.
A(n) ______ is a numerical summary of a sample.
A statistic is a numerical summary of a sample.
A(n) ______ is a numerical summary of a population.
A parameter is a numerical summary of a population.
_________ are the characteristics of the individuals of the population being studied.
variables
What is the difference in a parameter and a statistic?
A parameter is a numerical description of a population characteristic.
A statistic is a numerical description of a sample characteristic.
Determine whether the variable is qualitative or quantitative.
Color of a car driven
The variable is qualitative b/c it is an attribute characteristic.
Determine whether the quantitative variable is discrete or continuous.
Freq. of a guitar note
The variable is continuous b/c it is not countable.
What is the difference in a discrete and continuous variable?
A discrete variable is a quantitative variable that has either a finite number of possible values or a countable number of possible values.
The term “countable” means that the values result from counting, such as 0, 1, 2, 3, and so on.
A continuous variable is a quantitative variable that has an infinite number of possible values that are not countable.
Determine whether the quantitative variable is discrete or continuous.
Points scored in a college basketball game
The variable is discrete because it is countable.
What is the advantage of using SPSS over calculating statistics by hand?
a) This is how most quantitative data analysis is done in “real research” nowadays
b) It reduces the chance of making errors in your calculations
c) It equips you with a useful transferable skill
ALL OF THE ABOVE
In SPSS, what is the “Data Viewer”?
A spreadsheet into which data can be entered
How is a variable name different from a variable label?
It is shorter and less detailed
What does the operation “Recode Into Different Variables” do to the data?
Redistributes a range of values into a new set of categories and creates a new variable
How would you use the drop-down menus in SPSS to generate a frequency table?
Click on: Analyze; Descriptive Statistics; Frequencies
Why might you tell SPSS to represent the “slices” of a pie chart in different patterns?
If you do not have a colour printer, it makes the differences between the slices clearer
In which sub-dialog box can the Chi Square test be found?
Crosstabs: Statistics
To generate a Spearman’s rho test, which set of instructions should you give SPSS?
Analyze; Correlate; Bivariate; [select variables]; Spearman; OK
Determining a Raw Score (X) from a z-Score
X = μ + zσ
The value of zσ is the deviation of X and determines both the direction and the size of the distance from the mean.
what does Normal distribution (Gaussian distribution) look like?
A symmetrical, bell-shape that describes the distribution of many types of data; most scores fall near the mean (68 percent fall within one standard deviation of it) and fewer and fewer near the extremes.
how to calculate variance?
The average of the squared difference from the mean.
What is Central tendency?
Average of a set of data (mean, median and mode).
The grades on a math midterm are normally distributed with mean of 67% and a standard deviation of 2.5. Greg scored a 70%. What is his z-score?
1.2
Richard grows prize winning pumpkins. He grows a pumpkin which weighs 450 pounds and enters it into a contest. The average weight of pumpkins in the contest is 320 pounds with a standard deviation of 75 pounds. What percentage of pumpkins weigh more than Richard’s pumpkin?
The z-score is 1.73, so the percentage of people with pumpkins weighing less than Richard’s is 95.82%. This means that only 4.18% of pumpkins weighed more than his.
What is measure of dispersion used to describe?
used to describe the spread of data items in a data set.
What are the two most common measures of dispersion?
range and standard deviation.
What are the 2 basic approaches to research design?
Comparative design
Correlational design