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Research Methods in Psychology CH9
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Terms in this set (32)
Positive correlation
A relationship between variables X and Y such that a high score for X is associated with a high score for Y and a low score for X is associated with a low score for Y
Negative Correlation
A relationship between variables X and Y such that a high score for X is associate with a low score for Y and vise versa
Pearson's r
Measure the size of a correlation between two variables; ranges from a perfect positive correlation of +1.00 to a perfect negative correlation of -1.00; if r=0 then no relationship exists
Scatterplot
A graph depicting the relationship shown by a correlation
Restricting the range
occurs in a correlational study when only a limited range of scores for one or both of the variables is used; range restriction tend to lower correlations
Coefficient of determination (r^2)
For two correlated factors, the proportion of variance in one factor that can be attributed to the second factor; found by squaring Pearson's r
Regression Analysis
In correlational research, knowing the size of a correlation and a value for variable X, it is possible to predict a value for variable Y; this process occurs through a regression analysis
Regression Line
Summarizes the points of a scatterplot and provides the means for making predictions
Criterion Variable
In a regression analysis, the variable being predicted from the predictor variable (college grades are predicted from SAT scores)
Predictor variable
In a regression analysis, the variable used to predict the criterion variable (SAT scores are used to predict college grades)
Directionality Problem
In correlational research, the fact that for a correlation between variables X and Y, it is possible that X is causing Y but it is also possible that Y is causing X; the correlation alone provides no basis for deciding between the two alternatives
Cross-lagged Panel correlation
a type of correlational research designed to deal with the directionality problem, if variables X and Y are measured at two different times and if X precedes Y, then X might cause Y but Y cannot cause X
Third Variable Problem
The problem of drawing causal conclusions in a correlational research; third variables are uncontrolled factors that could underline a correlation between variables X and Y
Partial correlation
A multivariate statistical procedure for evaluating the effects of third variables; if the correlation between X and Y remains high, even after some third factor Z has been partialed out, then Z can be eliminated as a third variable
Split-half reliability
A form of reliability in which half of the items (even numbered items) on a test are correlated with the remaining items
test-retest reliability
A form of reliability in which a test is administered on two occasions and the correlation between them is calculated
Criterion validity
Form of validity in which a psychological measure is able to predict some future behavior or is meaningfully related to some other measure
Interclass correlation
A form of correlation used when pairs of scores do not come from the same individual, as when correlations are calculated for pairs of twins
Bivariate
A statistical analysis investigating the relationship between two variables
Multivariate
A statistical analysis investigating the relationships among more than two variables
Multiple regression
A multivariate analysis that includes a criterion variable and two or more predictor variables; the predictors have different weights
Factor analysis
A multivariate analysis in which a large number of variables are intercorrelated; variables that correlate highly with each other form factors
A study using a ________ helps to solve the directionality problem.
A) cross-lagged panel correlation
B) partial correlation
C) multiple regression
D) factor analysis
A) cross-lagged panel correlation
When is correlational research preferred over experimental research?
A) whenever the researcher wishes to determine cause and effect relationships
B) whenever the researcher prefers to do field rather than laboratory research
C) whenever the study includes factors that cannot possibly be controlled
D) never — experimental studies are always preferred
C) whenever the study includes factors that cannot possibly be controled
In a negative correlation,
A) high scores on one variable are accompanied by high scores on the second variable
B) low scores on one variable are accompanied by low scores on the second variable
C) high scores on one variable are accompanied by low scores on the second variable
D) both alternatives a. and b.
C) high scores on one variable are accompanied by low scores on the second variable
In a study examining the relationship between A and B, the coefficient of determination
A) indicates how much variability in A can be accounted for by B
B) is found by squaring the value of Pearson's r
C) both alternatives a. and b.
D) none of the above
C) both a and b
Suppose there is a high positive correlation between reading speed and reading comprehension. You suspect that IQ is a potential third variable. You complete a partial correlation procedure and, with IQ controlled statistically, the high correlation between speed and comprehension virtually disappears. What do you conclude?
A) IQ is an important third variable affecting the correlation
B) IQ can be ruled out as a third variable underlying the correlation
C) IQ must be the cause of the correlation
D) not enough information to decide
A) IQ is an important third variable affecting the correlation
Picture a regression line as a diagonal line running from the lower left to the top right on a scatterplot. For which of the following correlations would the points be closest to this regression line?
A) -.90
B) -.30
C) +.40
D) +.70
D) +.70
The same interpretation problems found in correlational studies also occur in
A) experimental studies
B) studies with subject variables
C) mixed factorial studies
D) repeated-measures studies
B) studies with subject variables
If there is a strong correlation between variables A and B, what is the most likely explanation?
A) A is causing B
B) B is causing B
C) A and B are caused by C
D) could be any of the above — the correlation by itself does not allow one to decide
D) could be any of the above - the correlation by itself does not allow one to decide
A researcher administers several tests, correlates each test with every other test, and looks for tests that cluster together. The researcher is probably performing the preliminary steps of what procedure?
A) multiple regression
B) partial correlation
C) factor analysis
D) criterion validity
C) factor analysis
In order for a Pearson's r to reflect a meaningful relationship, which of the following must be true?
A) the relationship must be nonlinear
B) the variables must be measured on at least an ordinal scale
C) the range of scores must be restricted on at least one of the variables
D) the variables must be measured on either an interval or a ratio scale
D) the variables must be measured on either an interval or ratio scale
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