ANOVA

If the independant variable has no effect, which means the group means are zero, what should the value of F be

1

What 4 things does the "F statistic" take into consideration

1)#of samples taken 2)sample size of each sample 3)means of the samples 4)standard deviations of each sample

What are the 2 sources of variation

1)Between group variance 2)Within group variance

What are the 3 assumptions needed for ANOVA

1)Randomly sampled 2)Dependant variable is normally distributed 3)homogeneity of variances

How many degrees of freedom do we need to know for an F-test and what are they called

2 degrees of freedom dfb = between group degrees of freedom (#of nominal categories - 1) dfw = degrees of freedom for within groups (number of subjects - number of categories)

how many means can a One-way ANOVA compare

3 or more independant means

Give a one way ANOVA example using car company with factories

A car company has 3 factories. Determine whether the mean mileage of cars produced by each factory is statistically the same

Can we conclude that all means are different from one another by rejecting the null?

No, only that they are not all the same

what levels of measurement can your independant variable be in an ANOVA

Nominal Ordinal

What are the 3 types of ANOVA

One way Two way N-way

What is a Repeated Measures ANOVA an extension of

a dependant group t-test

Whats the alternative hypothesis for ANOVA

at least some of the group means are not equal

How is the indepedant variable different across multiple measurements

either by representing different treatments or different time periods

Give an example of a 2 way ANOVA using car company with factories

has two categories of defining caracteristics

When can the normality assumption be violated

if the sample size of the group is >20

when can the homogeneity of variances assumption be neglected

if the sample sizes are similar

What type of test is a One way ANOVA an extension of

independant groups t-test

What levels of measurment does your dependent variable have to be in an ANOVA

interval ratio

What does "Partitioning Variance" mean, and what does it involve

it is a key concept of ANOVA that involves isolating reasons why peoples scores might differ from others

In a Repeated Measures ANOVA, are measurements taken multiple times for the same group of people or for multiple groups

measurements are taken for the same people

Give an example of a N-way anova using car company with factories

multiple number of factors

If only 2 group means are being compared, what may be used instead of ANOVA

t-tests

Whats the null hypothesis for an ANOVA

the group means are equal

What is a "grand mean"

the mean of the means

What is the purpose of an ANOVA

to determine whether data from several groups have a common mean

Using the F statistic, when do you reject the null hypothesis

when (tabled F)<(Calculated F)

What does ANOVA stand for

Analysis of Variance

What does the F Statistic, otherwise known as the F ratio, contrast

Between group variance divided by within group variance

In the following example, identify the independant and dependent variable. "We have randomly assigned 15 MI patients to 1 of 3 different therapies. After each therapy, we measured their stress from 0-10

Independant variable: Only 1, being therapy Dependant variable: Stress

If the variation between sample means is greater than the variation in each sample, will the F stat be large or small

Large

What statistic tests the homogeneity of variances

Levene's statistic