research lecture 6 Flashcards
if it’s a two-tail test….you interpret the p
value in SPSS using ___. SPSS is adjusting it for
you (dividing it in half)
.05
if you need to adjust the alpha
further…ex/ Bonferroni adjustment for 2 t-
tests….then compare the SPSS p-value to ___
to determine significance.
.025
what is the difference between T-test and ANOVA
T-test: compares 2 means and only has one IV
ANOVA: compares 3+ means and only used when u have more then 1 IV
can you use a T- Test from a one way repeated measures
yes bc only 1 IV
can you use a T-test from a posttest only randomized group and posttest only non randomized
yes
if we want to compare several means why don’t we
compare multiple pairs of means with t-tests?
inflates the type 1 error rate
like a t-test, ANOVA tests the ____ hypothesis that the means are approximately the same.
null
what does a experimental hypothesis mean for an ANOVA
the means differ between each other
ANOVA is an ____ test
Omnibus
ANOVA is an Omnibus test .. what does it test, tell us and doesn’t tell us
-It tests for an overall difference.
– It tells us that the means are different.
– It doesn’t tell us exactly which means differ.
what is An “overall test“ - tests a number of different comparisons at once
omnibus
what does an 2x3x4 ANOVA tell us
3 IV
on has 2 variables
one has 3 variables
one has 4 variables
what ANOVA is it called if there is 2 or more IV ar least one is independent and one is repeated
2+x2+ mixed or split plot ANOVA
how do u find the mean squares
sum of squares / degree of freedoms
how many DF is there for an ANOVA
these are always 2 .. one has to do with the amount of groups minus 1 and other one has to do with the number of ppl
can the F result from the omnibus ANOVA tell us if it is significant
no not by itself
a significant omnibus (global) test tells us that there is a difference among the ___ or the group ___ are different somewhere
means 2x
what does a significant omnibus does not tell us
specifically which group means different from which
do you use follow up test with a significant omnibus test
yes always
how do you do follow up test for an omnibus test?
planned contrasts or post HOC comparisons
do not use multiple t test
is a planned contrasts or Post HOC comparisons get significance easier ?
planned
what is a planned contracts
planned prior
ex: u only want to compare
the placebo group to each tx.
group.
what is a post HOC comparisons
not planned (no hypothesis)
compares all paris of means
when do u use a post hoc
any stat test after global omnibus ANOVA (usually has 2 means)
what do u run after global (omnibus test) and have significant interaction
simple effects
when do u do a pairwise
usually after global test (only 2 means)
what are the post hoc statistical test designed to control
the alpha level ( basically control the family wise (overall) error rate)
what are the 3 most common post hoc test
- bonferroni
-turkey
-games-howell