chapter 27: ANOVA

Question 1

The equation for analysis of variance F statistic takes this form

Answer 1

Question 2

ANOVA tests:

Answer 2

whether several populations have the same mean by comparing how far apart the sample means are with how much variation there is within the samples.

Question 3

comparing several means is called

Answer 3

one way ANOVA

Question 4

true or false: The F statistic can take only values that are zero or positive

Answer 4

true

Question 5

When the alternative hypothesis is true, the variability in the sample means will be _____.

Answer 5

large

Question 6

The results of the ANOVA F test are approximately correct when the largest sample standard deviation is no more than _____ as large as the smallest sample standard deviation.

Answer 6

twice

Question 7

brief notation for the F distribution

Answer 7

F(df1, df2) where df stands for degrees of freedom (numerator then denominator)

Question 8

how to determine the degrees of freedom

Answer 8

I = number of populations/means

N = number of total observations

so I-1/N-I

Question 9

an example of interpreting small p-value would be:

Answer 9

Since the P-value is fairly small (0.012 < 0.05), we reject the null hypothesis that all three population means are equal and conclude that at one mean differs from the rest

Question 10

It is not a necessary condition for all sample sizes to be equal, but it does help if:

Answer 10

there is doubt regarding the equality of the population standard deviations

Question 11

how to perform one-way ANOVA in SPSS

Answer 11

1. Analyze > Compare Means > one-way ANOVA
2. plug in response/dependent and factor/explanatory
3. click options
4. check “descriptive” and “means plot”
5. click continue and ok
6. “Sig.” is P-value

Tukey:

1. click Post-Hoc and Tukey