Flashcards in Lecture 10 Deck (18):

1

## Correlation coefficient

### a measure of the strength of association or relationship between 2 variables.

2

## Covariance:

### a measure of the average relationship between 2 variables. It is the average cross-product deviation (i.e., the cross-product divided by one less than the number of observations).

3

## Coefficient of determination:

### the proportion of variance in 1 variable explained by a 2nd variable. It is Pearson’s correlation coefficient squared.

4

##
Cross product deviations:

### a measure of the ‘total’ relationship between 2 variables. It is the deviation of 1 variable from its mean multiplied by the other variable’s deviation from its mean.

5

##
Curvilinear relationship:

### in general, curvilinearity is a upside-down U shape distribution.

6

## Dichotomous variable:

### nominal variable that consists of only 2 levels/groups

7

##
Truncated range:

### Refer to situations in which the sample is somehow limited. also called a restricted range.

8

## Pearson’s r:

### standardized covariance

9

##
What are the two fundamental characteristics of correlation coefficients? Be able to define each.

### Direction (pos/neg) and magnitude (strength… how close to +1 or -1)

10

##
When the correlation coefficient is zero, what is the relationship between the X and Y variable?

###
no relationship

11

##
What is a perfect positive correlation? What is a perfect negative correlation?

### +1 and -1

12

##
When would you compute the following correlation coefficients: Pearson product-moment correlation, point-biserial correlation, biserial correlation, phi coefficient, Spearman’s rho? Note: remember the type of correlation depends on the scale of measurement of the X & Y variables (e.g. dichotomous, nominal, ordinal, continuous).

### sdlafkj

13

##
Be able to list and define/describe all of the issues discussed in class that may weaken (or attenuate) the correlation coefficient.

###
1. Outliers: extreme scores

2. Truncated range: restricted range/variance

3. Curvilinear relationship: nonlinear relationship that Pearson’s r cannot model

14

## outliers:

### extreme scores

15

## truncated range

### restarted range/variance

16

## curvilinear relationship

### nonlinear relationship that person's r cannot model.

17

##
Be able to interpret a 95% confidence interval around a sample correlation coefficient.

###

CI95= The mean +/- (1.96)(standard error of the mean)

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