ANOVA exam
The degrees of freedom between groups for the interaction
(dfA x B) is dfA times dfB
Which is correctly written: 1. F(83)=# 2. F (83, 84)=# 3. T (78, 43)= #
2
The statistic for the ANOVA is
F
When ___is significant, it indicates that across all group means, there is a significant difference due to the independent variable.
Fobt
The degrees of freedom total equals
N - 1
The degrees of freedom within groups equals
N - kA x B
The critical value of F (Fcrit) depends on
The degrees of freedom (both the dfbn = k - 1 and the dfwn = N - k) The α selected
This type of variability tells us if our independent had an effect on our dependent variable.
between groups variability
how do 0mg scores differ from 10 mg scores, etc. look at different levels. Can also compare grand mean ( mean of all levels combined) how does the mean of 5mg differ from the grand mean?
between groups variablity
the degree to which the scores of different treatment groups differ from one another or the grand mean.
between groups variablity
show the second factor on a graph by
drawing a separate line connecting the means for each level of that factor
When there are more than two means in an experiment, using multiple t-tests results in an
error rate much larger than the one we have selected (α).
An independent variable is called a
factor
The independent variable matches which of the following ANOVA terms?
factor
hypothesis for ANOVA
ho: m1=m2=m3 ha: not all m's are equal
Lines cross:
interaction
When graphed, a significant interaction effect produces two or more lines that
intersect
dependent variable must be in what measurement
interval or ratio (scale)
The symbol for the number of levels in a factor is
k
The degrees of freedom between groups for factor A is
kA - 1
The degrees of freedom between groups for factor B is
kB - 1
Each condition of the independent variable is also called a ___ or a ____
level, treatment
the F test is a one or two tailed test
one
performed when only one independent variable is tested in the experiment
one-way anova
along the X axis,
place the levels of one factor
ANOVA does not indicate which
specific means differ significantly
along the Y axis
the dependent variable means
Using the ANOVA allows us to compare the means from all levels of the factor and keep
the error rate equal to α.
the effect that changing the levels of that factor has on dependent variable scores, while ignoring all other factors in the study.
the main effect of a factor
differences produced by the independent variable are a
treatment effect
When an experiment design has two factors but one factor involves related samples while the other factor involves independent samples, we should perform a
two way anova, mixed design
is present when the relationship between one factor and the dependent scores changes as the levels of the other factor change.
two way interaction effect
performed when two independent variables are tested in the experiment
two-way anova
When both factors involve independent samples, we perform the
two-way, between-subjects ANOVA
When one factor is tested using independent samples and the other factor using related samples, we perform the
two-way, mixed-design ANOVA
When both factors involve related samples, we perform the
two-way, within-subjects ANOVA
When the F-test is significant,
we perform post hoc comparisons on all pairs of treatment groups.
when do we use analysis of variance
when data are interval or ratio level and there is at least one independent variable with three or more levels.
variability within a single level. Thus, variability between participants JUST in the 0 mg level.
within groups
the degree to which the scores of subjects in the same treatment group differ from each other
within-groups variablity
When an experimental design has two factors and both factors are tested using related samples, we should perform a
within-subjects two way anova
refers to the interaction between the two factors
A x B
Assumptions of ANOVAs
All conditions contain independent samples The dependent variable measures normally distributed interval or ratio scores The variances of the populations are homogeneous
what does ANOVA stand for
Analysis of variance
