Z-scores, T-tests, etc Flashcards
raw score, sample mean, SD,
Z-score
(raw score-s.mean)/SD
z-score
SD, number of samples
Standard error
it gives an estimate of the precision of the sample mean
standard error
sample mean, hypothesized population mean, population SD, sample size
Z-test
How to find a raw score from a z-score?
raw score= (Z-score*SD)+ s.mean
(s.mean - p.mean)/(pop standard deviation/√sample size)
Z-test
Do we use Z-score or T-test when the population Standard Deviation is unknown?
T-test
Do we use Z-score or T-test when the sample size is smaller than 30?
T-test
(sample mean-population mean)/(sample standard deviation/√sample size)
T-test
Which way does the <> face for one way decision criteria?
>
How do you calculate the SD for a sample?
Use excel lol
what are the steps for such a problem: For a normally distributed set of scores, what percentage of raw scores fall between a z-score of +0.83 and a z-score of +2.15?
- find p-value in z-table for both
2. smaller number- larger number
Does a z p-value show the percentage of all the scores on the left or on the right of the score
on the left of the score
How to find the decision criteria, z-tests and t-tests?
Look in the z/t table for score that correlates to the alpha/significance level you’re searching for. (.05, .025, etc)
If you are doing a two tailed test and the significance level is .05 how should you find your decision criteria?
Search for .025 in the relevant table
How to find the decision criteria for chi-square?
- calculate DF =(row-1)(column-1)
2. find the value at the intersection of the probability/significance level/alpha
Why do we use ANOVA and not T-tests?
Type I Error rate compounds if we compare 3 or more tests using T-tests.
Why do we want a big number from an ANOVA test?
If it’s big then the means of each sample are far apart and the distributions are small/narrow
ANOVA= variance between distributions/variance within distribution
What is the result that comes out of an ANOVA called?
F-test statistic
What do chi and ANOVA have in common?
- Want big number as result
- Positive skew (no neg numbers)
What do chi and ANOVA have in common?
- Want big number as result
- Positive skew (no neg numbers)
Difference between one-way and factorial ANOVA?
1-way has one independent variable (IV)
Factorial is 2+
Maximum amount of independent variables you’ll normally see in an experimental deisgn?
3, more and it get’s quite complicated
Can a Z value be negative?
no
