Categorical Predictors Flashcards
what is the f statistic?
ratio –> variance explained by the model : variance unexplained by the model
what is dummy coding?
coding any categorical predictor
what are the dummy coding labels?
b0 = control / b1 = control and variable 1 / b2 = control and variable 2
what are the three ways to test for homogeneity of variance?
Levene’s, variance ration, robust F statistic
when and how would you use a Levene’s test?
shouldn’t due to problems with he sample size
when and how would you use a variance ration?
divide the largest variance by the smallest variance / any number <2 is good
when and how would you use the robust F statistics?
the Welch and Brown-Forsythe should share a similar statistic and significance
what does a symbol mean if it has “^” above it?
an estimate of
what is cohen’s d?
a measure of effect size
what do you do if you are able to use a control group?
^d = the difference between the two means / SD of control
what do you do if there is no control but the two groups have equal variances?
^d = the difference between the two means / SD of either group
what do you do if there is no control and the two groups have unequal variances?
a pooled estimate to create the number that the difference between the two means is divided by
how do you calculate the pooled estimate?
(sample 1 - 1) x s1^2 (sample 2 - 1) x s2^2 / (sample 1 + sample 2) - 1
square root the answer
