ERMS Exam 3 Flashcards
ANOVA
Analysis of variance
Variance
measure of statistical dispersion, how far from the expected value its values typically are
why do we use
ANOVA
used to evaluate mean difference between 2+ groups
Multigroup research
contains more than 2 groups
Factor
the independent (or quasi-independent) variable that indicates the groups that are being compared
Factorial design
study design that has 2+ factors (aka, more than 1 IV)
Levels
conditions or values that make up a factor
Alpha
tells us how often we should expect to mistakenly reject a null hypothesis
ANOVA Null hypothesis
There is no difference, anywhere, between ANY groups.
ANOVA Alternative Hypothesis
there is a difference, somewhere, between at least 2 groups.
F-Statistic
Divides the variance (differences) we see between our sample means by the variance we would expect if there was no effect ???
f-statisitic formula??
Between groups Variance + error / Within groups Variance
ms between/ ms within?
Between-treatment variance
the variance between groups, systematic treatment affects, but unsystematic factors.
is the denominator of f-ratio
Within treatments Variance
Random, unsystematic factors, Denominator of f-ratio.
Within-groups Variance
Variability that naturally occurs within a level/condition, Comes from people having naturally different scores within a group
One-way ANOVA
Uses 1 categorical IV with 3+ levels
Factorial ANOVA
Uses 2+ categorical IV with 2+ groups
K
number of groups
N
Number of participants
Post Hoc tests
Follow-up tests done to determine exactly which mean differences are significant and which are not.
Planned comparisons:
when researcher make plans ahead of time: Plan which pairs of groups\levels they intend to compare
how do Bonferroni Correction tests work
Series of T-test for every possible pair of groups, Is going to correct for family wise error inflation by dividing alpha by the number of tests giving you a new alpha.
alpha/# of tests = new alpha
Tukey’s HSD
Honestly significant difference, makes adjustment to deal with inflated family wise error.
Determines the minimum difference needed to have statistical significance at that alpha level
Confidence interval
A range of scores that extends equally in both directions from an estimate that are considered plausible based on the data
(the scores that are liekly 95%).