Exam 3 Flashcards
Population
The entire set of people or products in which you are interested
Sample
A smaller set, taken from the population
Census
The whole population
Probability Sampling
Every member of the population has an equal chance at being selected
Simple Random Sampling
Randomly selected from the list of all those in the population
Random Assignment
Used only in experimental designs to assign participants to groups at random
What is the difference between probability and non-probability sampling?
In probability sampling, each member has an equal chance of being included in a sample, but in non-probability sampling, members are not selected at random
Self Selection
Sampling only those who invite themselves
Quota Sampling
Identify subsets of the population (strata), then use convenience/snowball sampling technique until quotas for each set are reached
Sampling Frame
The actual populations of individuals (or clusters) from which a random sample will be drawn
Response Rate
The percentage of people in the sample who actually completed the survey
What does the difference between respondents and non-respondents limit?
The generalizability of the study
Why are large samples generally better than small samples?
There is a greater power to detect differences
Confidence Interval
A calculated interval of values within which there is a chosen level of confidence (e.g. 95%) where the true population value lies
What is most important about the sample?
How it was selected
What does a large sample size equal?
A small margin of error
Bivariate Correlation
An association that involves exactly two variables
What is a quantitative variable?
Score, Height, Measure
What is a categorical variable?
Eye color, genre, major
T-Test
A statistic used to test the differences between two group averages
What makes a study correlational?
Measured Variables
What statistics are used to analyze association claims?
Scatterplots, bar graphs, r test, t test, and ANOVA
The Steps to Describing Associations are:
Step 1: Consider the scatterplot or bar graph
Step 2: Consider the test statistics
Step 3: Describe the result in APA Style
What do you ask when interrogating construct validity?
How well was each variable measured?
What do you ask when interrogating statistical validity?
How well do the data support the conclusion?
What do you ask when interrogating internal validity?
Can we make a causal inference from association?
What do you ask when interrogating external validity?
To whom can the association be generalized
Effect Size
Describes the strength of an association
P Value
Probability estimate of the likelihood that the sample came from a population with a relationship of zero.
What value of P is usually considered statistically significant?
p < .05
What happens if p is relatively high?
The result is not statistically significant
Curvilinear Association
The relationship between two variables is not a straight line
Longitudinal Design
measures the same variables in the same sample at multiple points
What is another name for longitudinal design?
Cross-lag panel design
Cross Sectional Correlations
Whether two variables measured at the same point in time are correlated
Autocorrelations
The correlation of each variable with itself across time
Cross-lag correlations
The correlation of an earlier measure of one variable with a later measure of the other variable; change over time
Instead of a longitudinal design, why not just do an experiment?
We cant always randomly assign participants to a variable
Define “Control For”
holding constant
What is the criterion variable?
The dependent variable
What is the predictor variable?
Independent variable
Parsimony
the degree of which a scientific theory provides the simplest explanation of some phenomenon
Mediation
Attempts to explain the relationship between two variables by testing for another variable that mediates the relationship between the first two
