statistical tests + errors Flashcards
what is a type I error
when the null hypothesis is true but rejected
what is a type II error
when the null hypothesis is false but accepted
what is generally considered worse, a type 1 error or a type 11 error?
a type 1 error (saying there is a difference when there isnt)
what probability level is the most stringent?
0.01
which probability level causes a type I error?
0.5
which probability level causes a type II error?
0.01
why do psychologists use a 5% significance level
it is a good compromise between being too strict and too lenient + reduces type I errors
what are the three factors in determining a statistical test
difference or correlation?
data type?
related or unrelated?
what is nominal data?
data is in separate categories
what is ordinal data?
data is ordered in a subjective way (rating scales)
what is interval data?
data is measured using units of equal intervals, standardised and objective
when do you use the sign test?
difference
nominal
related (repeated measures)
when do you use a Mann Whitney U test?
difference
ordinal
unrelated (IGD)
when do you use a wilcoxon matched pairs test?
difference
ordinal
related
when do you use a chi squared test?
difference
nominal
unrelated
