Research Methods Flashcards
Independent Variable
The variable whose effect is being studied
Dependent Variable
The variable expected to change due to variations in the independent variabble
What is the difference between a true experiment and a quasai experiment and correlational study.
True experiment: Independent var is manipulated, subject is randomly assigned to different groups
Quasi: no random assignment
Correlational study: no manipulation of independent var
What is another name for a naturalistic observation?
A field study
Population is
The total number of subjects that fit into a specific characteristics. i.e. people whom live in the US. People over 40 etc.
Sample
Is a sampling of people that is representative of the larger population.
The best way for researchers in getting an accurate sample?
A random sample.
What is another type of random sample?
Stratified random sample
What does a random stratified sample
It is a random sample that includes specific groups in proportion with the larger population. An attempt to get a more accurate measure.
Describe Between subject design
subject is exposed to only one level of independent variable. The subjects are assigned ranomly to groups and subjects are not given the same level of IV as another group.
Can groups differ on chance even with random selection?
Yes
What is matched subject design
Where the experimenter matches the two groups. So that people with similar abilities or characteristics are matched together and then studied together. For example if there is variability of intelligence between groups and intelligence is the dependent
What is within subjects design research
The subjects own performance is the basis of comparison. The crucial thing here is that the subject is exposed to more than one condition, allowing the researcher to separte the effects of individual differences in intelligence from the effects of the IV. A-B, A-B-A etc
What are the most obvious problems in research design
Experimenter bias
Demand Characteristics
Placebo Effect
Hawthorne Effect
Describe the placebo effect:
When people show positive effects to sham treatment, intert substances, or no active treatment.
What is the Hawthorne effect
The effect that being observed has on behavior
Describe demand characteristics
Cues in research situations that suggest to the subject what is expected.
Describe experimenter bias
How the experimenter biases the study in all aspects, methods, statistics, design and reporting.
What are the two major categories of statistics?
Descriptive and inferential
What is descriptive statistics concerned with?
Is concerned with organizing, describing, quantifying, and summarizing a collection of actual observations.
What is inferential statistics concerned with?
Inferential statistics researchers generalize beyond actual observations.
Frequency distributions
A chart that is used as a graphic representation of the frequency of one variable of the data.
Measures of central tendency are
mean, median and mode
mode
Is the most frequent value
If there are two modes, what is it called?
Bimodal
A distribution can have 3 or 4 modes
then it is polymodal
Median is the central number
Count the numbers and figure out which one is exactly in the middle. If even average the two middle numbers.
Mean
Is the average of the data across all subjects. Or in otherwords the numerical 50%
What are numbers that don’t fit the central tendency?
outliers
What is the most sensitive measure to extreme outliers?
mean
What are measures of variability
Range
Standard deviation
variance
Variability or dispersion scores
Range
Is the smallest number subtracted from the largest
Standard deviation
The average scatter away from the mean. (square root of the variance)
Variance
The square root of the STD
What is a normal distribution
It is a bell shaped curve of the data that follows a typical pattern.
With normal distribution how can you tell the percentile of the score the person is in?
By using the z-score
What is the z-score?
The number of STD away from the mean.
What is 1 z score account for
34% on one side of the distribution, 68% on both sides
What does 2 z score account for
14% or 13.6% between 1 and 2, aprox 48.5% on one side of the distriubution and aprox 97% on both sides
What is above 2 zscore
1.5% on one side or 3 % on both sides
What is a T-score?
It is a standardize score with a STD of 10. Often used for test scoring because of the nice even round numbers.
What is a non-normal distribution?
When the data does not fit a normal distribution
If the mean is less than the median then
the data is skewed to the left (lower numbers)