[L9] Analysis of Variance & [L10] The Kruskal-Wallis Test Flashcards
- Very flexible and general technique, and the principles
can be applied to a wide range of statistical tests.
ANOVA
ANOVA is a ___ test
parametric
Has a wide range of applications.
ANOVA
Many of applications make some tricky assumptions
about the data.
ANOVA
In ANOVA we measure an ___ variable (also called
a ___ variable).
* This outcome must be measured on a ___ scale.
outcome; dependent - continuous
It is called dependent because it depends on one or more
__ variables
predictor
__
_ variables can be Manipulated (Treatment) or
variables we simply measure (Sex).
Predictor
In ANOVA, predictor variables are mostly ___,
although continuous variables can also be used in the
same framework
categorical
When predictor variables are categorical, they are also
called “__“_
FACTORS or INDEPENDENT VARIABLES.
___ – measurement of differences
ANOVA
Differences happen for two reasons: ___
(a) because of the
effect of predictor variables (b) because of other reasons
In ANOVA, we want to know two things:
___
- How much of the variance (difference) between the
two groups is due to the predictor variable
- How much of the variance (difference) between the
- Whether this proportion of variance is statistically
significant, that is, it is larger than we would expect by
chance if the null hypothesis were true?
- Whether this proportion of variance is statistically
We can divide (statisticians sometimes say partition)
variance into three different types:
___
- The Total Variance
- Variance due to treatment, (Differences between Group)
- Variance due to Error (Differences within Group)
In ANOVA, the variance is conceptualized as sums of
_
__
squared deviations from the mean
In ANOVA, the variance is conceptualized as sums of
squared deviations from the mean.
* It is usually shortened to___ and denoted by
__
sum of squares; SS.
The 3 Sum of Squares
- Total Sum of Squares, SS total
- Between-groups Sum of Squares, SS between
- Error Sum of Squares, SS within
___– this is the variance
that represents the difference between the groups, and this
is called _
_
. Sometimes it refers to the betweengroups
sum of squares for one predictor, in which case it
is called SS predictor. Sometimes it is called___.
Between-groups Sum of Squares; SSbetween; SStreatment
The ___-groups variance is the variance that we are
actually interested in.
between
We are asking whether the difference between the groups
(or the effect of the predictor) is big enough that we could
say it is ___
not due to chance
_
_
_– also called within-groups sum
of squares.
Error Sum of Squares
It’s within the groups, because different people, who
have had the same treatment, have different scores.
Error Sum of Squares
They have different scores because of error. So this is
called either ___
SSwithin, or SSerror.
We need to calculate the three kinds of Sum of Squares,
___
TOTAL, WITHIN GROUPS, and BETWEEN
GROUPS.
_
_
_sum of squared differences between the mean
and each score.
SStotal –