1 Way Independent anova

Question 1

Independent t test, 1 IV with 2 conditions

Answer 1

Test whether there is a difference between the levels (conditions) of the factor (IV)

Takes measure of effect, compares to measure of unsystematic variance

Takes mean values and add them together to get grand mean

Between group differences= summed square difference between group means and grand mean multiplied by n and divided by df

Question 2

Between group differences include

Answer 2

The effect
- differences due to treatment

The error

• individual differences
• error (due to sampling)

Question 3

Within group variance= systematic variance

Answer 3

The error

• individual differences
• error (due to sampling)

Compare group means to ppt means

Squared difference between each score and the group mean, summed and divided by n-1

Question 4

F ratio

Answer 4

Within groups variance -> estimate of how much error we have in our effect

Between groups variance (effect + error) / within groups variance (error)

Dividing the effect (between groups) by the error (within groups) = value that represents our effect = F ratio

Indication of size of our effect taking the error in the measurement into account

If F is greater than 1 you have more effect than error
If F is smaller than 1 you have more error than effect

Question 5

Partial ETA squared

Answer 5

To work our size of our effect we need to calculate partial eta squared

np2= between groups variance / total variance (within + between groups variance)

Tells us what proportion of our total variance is due to treatment effect

Value converted into proportion eg 0.45= 45%

Question 6

Rounding

Answer 6

All values rounded to 2 decimal places except p value which is reported to 3

Question 7

P value

Answer 7

A significant value

Low probability that differences would be seen in the sample, if no effect in population

Question 8

Assumptions of a 1 way independent anova

Answer 8

Continuous dependent variable (DV)

Normal distribution

No outliers- box and whiskers plot

Equal variance- no differences between the error (within groups) variance in each group

Question 9

Reporting stats

Answer 9

F (effect df, error df) = [F value], p = [p value], np2 = [np2 value]

Question 10

Reporting not significant results

Answer 10

No differences between levels (groups) and no effect of the treatment

‘ a one way between ppts anova shower that there was no significant effects of …. on …. (report data)

Question 11

Reporting significant results

Answer 11

Differences between levels (groups) and effect of your treatment

‘A one way between ppts anova shower that there was a significant effect of ….. on the ….. (report data)’

If anova significant need to find out what groups differ