Chpt 12: Understanding Research Results: Description and Correlation (PSY302) Flashcards
3 basic ways to discrete your results of a study of relationships with between variables:
Comparing group percents
Correlating scores of participants on 2 variables
Comparing each group means.
Def: Frequency Distribution
a set of scores typically from lowest to highest which indicates the number of times each score was obtained.
Def: Frequency polygons
uses a line to represent the frequencies of scores.
Def: Descriptive stats
precise statements of data taken from statistical math.
Def: Central tendency
a way to value the central score of each set.
Def: Variability
the amount of spread in a distribution of scores.
Def: Standard deviation
the average deviation of scores taken from the mean.
Def: Variance
the square of the SD
Def: range
Range: the diff between the highest score and the lowest.
_____ graphs are used when the values on the x axis are __________ categories.
Bar, nominal
_____ graphs are used when the values on the x axis are __________.
Line, numeric
Choosing the scale for a bar graph allows a common __________ that is sometimes used by scientists and often used by advertisers.
manipulation
Def: Correlation coefficient
a stat that describes how strongly variables are related to one another.
Def: Pearson product moment correlation coefficient
used when both variables have interval or ratio scale properties; called the Pearson r.
Provides info abt both the strength & the direction of the relationship.
Values can range from 0 to 1.00.
Results can be described visually using a scatter plot where each pair of scores is shown as a single point on a diagram.
If the range of possible value is __________, the magnitude of the correlation coefficient is _________.
restricted, reduced
Def: Restriction of range
an issue when scores on a variable are limited to a small subset of their possible values, making it more difficult to identify relationships for the variable to other variables of interest.
The Pearson product r is designed to detect only _____ relationships.
linear
If the relationship is curvilinear, the correlation coefficient will ____ indicate the existence of a relationship.
not
Def: Effect size
Effect size: the strength of association between variables.
The Pearson r correlation coefficient is one indicator of effect size; it indicates the strength of the linear association between 2 variables.
Small effects are near_______
Medium moderate effects are near ______
Large effects are above r = 50
Squared value of the coefficient r squared transforms the value of r to a ___________.
r=10, r = 30, percentage
Reporting effect size provides a scale of ______ that is __________ across all types of studies.
values, consistent
Def: Regression equations
Regression equations: calcs used to predict a person’s score on one variable when that person’s score on another variable is already known.
Y=a+bX where Y is the score we wish to predict, X is the score that is known, a is a constant, and b is the adjustment factor
To predict a future behavior (criterion variable) on the basis of one’s score on some other variable. It’s necessary to demonstrate that there is a reasonably _______ correlation between the 2.
high
Def: Multiple regression
Multiple regression: used to analyze the relationship between a criterion variable & more than one predictor variable.
Def: Multiple correlation
the correlation between a combined set of 2(+) predictor variables & a single criterion variable.
Symbolized as R
In research, a mediating variable is hypothesized to be intervening between variable ___________
X and Y
In a mediation model, the independent or predictor variable affects a ________ variable. The mediating variable then affects the dependent or ________ variable.
mediating, criterion
In research, a moderating variable changes or ______ the relationship between variable X and Y
limits
The 2 terms, moderation and interaction, developed from diff research traditions, but they mean essentially the ___________ when you interpret research findings.
same thing
When experimental research is properly designed, there’s no ___________ issue bc all extraneous variables are controlled, either by keeping the variable constant or by using ____________
3rd variable, randomization
Multiple _______ can be used to statistically control l for the effects of the 3rd variables.
regression
Def: Structural equation modeling (SEM)
Structural equation modeling (SEM): statistical techniques to evaluate a proposed set of relationships among variables.
After data has been collected, statistical methods can be applied to examine how closely the proposed model actually fits the obtained data
Researchers typically present path diagrams to visually represent the models being _____.
These show the theoretical ________ paths among the variables.
tested, causal
