# Shared Flashcard Set

## Details

Intermediate Statistics
Test C
38
Psychology
11/20/2013

Term
 To what does the term correlation refer?
Definition
 The association or relationship between variables in interval/ratio level data
Term
 What is a bivariate correlation?
Definition
 The relationship between one independent and one dependent variable
Term
 What is a scatterplot?
Definition
 The graphical display of two bivariate interval/ratio-level variables
Term
 What is a positive correlation between two variables?
Definition
 When the two variables have corresponding scores (e.g. when one goes up, so does the second)
Term
 What is a negative correlation?
Definition
 When high scores on one variable correlate to low scores on another variable
Term
 What does the term covariation mean?
Definition
 Scores on two or more variables that vary together
Term
 What is a regression line?
Definition
 A line drawn through the center of the data represented in a scatterplot
Term
 If the pattern of a set of data points and the line drawn through them has an upward slope, it has a ________ correlation
Definition
 Positive
Term
 The closer data points cluster around a line, the _______ the relationship between x and y
Definition
 Stronger
Term
 What is the Pearson correlation coefficient?
Definition
 The statistic used to measure the correlation between two interval/ratio level variables
Term
 What does Pearson's r measure?
Definition
 The strength of the linear correlation between two continuous (interval/ratio) variables
Term
 What is the statistic r?
Definition
 The sample estimate of the correlation between the two variables in the population
Term
 Rho (or ρ) stands for...
Definition
 The population correlation coefficient
Term
 Pearson's r indicates correlation using what range of numbers? What do the numbers mean?
Definition
 -1 through 1-1 is a perfect negative relationship, 0 is no relationship, and 1 is a perfect positive relationship
Term
 What are conditional distributions?
Definition
 The distribution of possible y scores for a fixed x score
Term
 What is the conditional mean of y?
Definition
 The calculated mean of y for every value of x
Term
 The y intercept is the point where...
Definition
 The regression line crosses the y axis (the value of y when x = 0)
Term
 The slope (aka the ___ ______ or the ______ _________) measures the amount of change produced in the y variable by a 1 unit change in the x variable
Definition
 Beta coefficient; regression coefficient
Term
 What is the residual when referring to regression analysis?
Definition
 The error between predicted and actual data
Term
 What is the main difference between the slope coefficient (b) and the correalational coefficient (r)?
Definition
 -b informs us about the way a relationship looks (if the relationship is negative or positive and how slanted the line is)-r standardizes b so that you can tell the strength of a relationship and compare this to other cases or variables
Term
 What are the 5 assumptions for testing hypotheses about the population slope and correlation coefficient?
Definition
 1- The observations were randomly selected2- Both variables have normal distributions3- The two variables are measured at the interval/ratio level4- The variables are related in a linear form5- assumption of homoscedasticity
Term
 What is the assumption of homoscedasticity?
Definition
 The error component is independent of and therefore uncorrelated with the independent or x variable, is normally distributed, and has an expected value of zero, and has a constant variance across all levels of x
Term
 How can the assumptions of homoscedasticity and linearity be assessed?
Definition
 By looking at the scatterplots. If the variance of y is the same for it's corresponding x, the conditions are met
Term
 What is a causal effect?
Definition
 The finding that a change in one variable leads to or produces a change in another variable, all other things being equal
Term
 What is nonspuriousness?
Definition
 The relationship between two variables is not caused by a third factor or factors related to them both
Term
 The multiple regression equation aims to...
Definition
 Estimate the effect of several independent variables on a dependent variable
Term
 What is a partial slope (or regression) coefficient?
Definition
 The partial slope of the linear relationship between each independent variable and the dependent variable
Term
 What is the additional assumption that is made for the multivariate regression model?
Definition
 The independent variables are not highly correlated among themselves
Term
 What is multicollinearity?
Definition
 Independent variables that are highly correlated with each other
Term
 Can you determine which IV has the strongest effect on the DV by comparing unstandardized partial slope coefficients?
Definition
 No, you must first standardize the slopes using beta weights
Term
 What is R^2 change?
Definition
 The change in the amount of variance explained when the second variable is entered into the regression model
Term
 What is a dichotomous variable?
Definition
 A variable that has only two outcomes (e.g. yes or no, did happen or did not happen)
Term
 What is a binary variable?
Definition
 A dichotomous variable that is coded as either 0 or 1
Term
 When is the ordinary least-squares regression model best used?
Definition
 In analyzing the relationship between independent variables and a continuous dependent variable that is normally distributed
Term
 When is the logistic regression model appropriate to use?
Definition
 When the dependent variable we have is a binary or dichotomous one
Term
 What is a linear probability model?
Definition
 One which assumes a linear relationship between an IV and the probability of a DV
Term
 If the logistic regression coefficient is positive, the value of the odds multiplier will be _____ than 1, indicating an increase in the odds of the DV occurring.
Definition
 Greater
Term
 What is the likelihood ratio statistic?
Definition
 A goodness of fit test for logistic regression which is -2 times the natural logarithm of the likelihood
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