ANOVA

Question 0

What is the variance between groups ?

Answer 0

Difference between the means of 2 groups

If it is far apart then the groups are not similar but if it is similar then the groups are considered to be similar

Question 1

What is ANOVA?

Answer 1

A statistical test used to analyse the differences between 3 or more groups
It tests the amount of variability between means of several groups with the amount of variability among the values within the groups

Question 2

What is variance within groups?

Answer 2

Comparing the standard deviations between 2 groups

If it is small then groups are not similar but if it is large then groups are similar

Question 3

What are t-tests ?

Answer 3

Statistical test used to determine whether the means of 2 independent groups were statistically different

Question 4

Why is multiple t-testing bad ?

Answer 4

Very tedious

Because the testing is normally at a 5% significance level if you did lots of test a type 1 error is likely to be caused

Question 5

What is a type 1 error ?

Answer 5

Claiming a difference when none exists or rejecting a true null hypothesis

Question 6

What is total degrees of freedom ?

Answer 6

It tells you the number of values which is able to vary

dft= dfw + dfb

Question 7

What is the sum of squares within (SSw) ?

Answer 7

Represents the amount of variability within groups

Question 8

What does the sum of squares between (SSb) mean?

Answer 8

Represents the differences between groups

Question 9

What is the total sum of squares ?

Answer 9

SSw + SSb

Question 10

What is degrees of freedom within (dfw) ?

Answer 10

Summing all the dfs within all groups

Nt-k

Question 11

What is degrees of freedom between (dfb) ?

Answer 11

Number of groups -1

K-1

Question 12

What is the mean square within (MSw) ?

Answer 12

SSw/dfw

Measure of the variability within groups - occurs by chance or sampling error

Question 13

What is mean square between (MSb) ?

Answer 13

SSb/dfb

Measure of the variability between groups - measure of how different the groups are from one another

Question 14

What is the Fobt ?

Answer 14

MSb/MSw
This is a ratio of the mean square values and tells you whether the difference between the groups are significantly greater than we would expect by chance
This value is compared with the Fcrit

Question 15

How is the intermediate X calculated ?

Answer 15

Grand total squared/total observations(Nt)

Question 16

How is the intermediate Y calculated ?

Answer 16

Sum of equal value in each squared

Question 17

How is the intermediate Z calculated ?

Answer 17

Add the value of the group together and square it and then divide by the amount in each group
Then add all groups together

Question 18

What does a high Fobt indicate ?

Answer 18

Indicates that the groups are different

Question 19

When is the Fobt statistically significant ?

Answer 19

If the Fobt is greater than the Fcrit then there is significance between some or all of the groups

Question 20

What are the underlying assumptions of t-tests and ANOVA?

Answer 20

Data are independent
Data are normally distributed
Variances of each group are equal

Question 21

What do you do if the data is not normally distributed ?

Answer 21

Use a non-parametric test
Use the Mann-Whitney test to compare 2 unmatched groups
Use kruskal-Wallis test to compare 3 or more groups

Question 22

What is the mean ?

Answer 22

Suitable measure of central tendency

Question 23

What is the standard error of the mean ?

Answer 23

Accuracy of estimated mean

Question 24

What is the standard deviation ?

Answer 24

Represents the spread of data

Question 25

What is correlation analysis ?

Answer 25

It is a significant relationship between 2 variables