Flashcards in Psych 202 - Test 3 Deck (12)

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1

## degrees of freedom

### the number of scores that are free to vary when estimating a population parameter

2

## why do we subtract by 0 in the mean

### we assume that the population and sample mean are the same, so there will be no difference (0) when subtracted from each other

3

## estimated variance

###
- we do not know the variance so we have to estimate it

- if the null is true and we pull the sample from the population, the means and standard deviations should be the same

- biased estimate with more likelihood of error

- sample variance will always be small than population variance

4

## divide by N - 1

### to correct for the biased nature of the estimated variance

5

## t-distribution

###
t < 30 = platykurtic

t > 30 = in between platykurtic and normal

6

## t-table

###
always go to lower number when looking at values

- rather be more conservative

- i.e. looking for 45 with choice between 43 and 50 --> go with 43 because we know we have 43 with our "group"

7

## t-test

### - used when population variance/standard error is unknown (our denominator in the final equation)

8

## ANOVA

### analyzes how much variance is due to randomness vs. how much is due to treatment/population differences

9

## difference score

###
change (A) - base (B)

> always subtracting the base from the specific

10

## between group variance

###
measures difference between the separate groups

- more difference expected than in within variance

11

## within group variance

###
measures difference within the separate groups

- ideally 0

12