Psych 202 - Test 3 Flashcards Preview

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Flashcards in Psych 202 - Test 3 Deck (12):
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

planned contrast

- within (group variance and df) stays the same
- between changes (group variance and df)
- recalculate the between variance and df with contrast scores instead of original data