# W8 - Effect Size Flashcards

1
Q

What do inferential statistics allow us to do?

A

Make conclusions about the pop based on sample statistics

2
Q

What can be HIGHLY influenced by the sample size

A

The p-value

Therefore whether the data shows it as being statistically different or not/

3
Q

Explain sample size + statistical significance

A

Very large sample size = Possible to get a significant effect when the real effect is very small

4
Q

What does a larger sample size result in for the representativeness of the sample of the population

A

Larger sample size = More representative the sample of the pop

5
Q

Larger sample size = More representative the sample of the pop

What follows?

A

Lower risk of sampling bias = ⬆️ reliability from a small effect

6
Q

Why is an effect size created?

A

To determine whether something is PRACTICALLY significant + meaningful in the real world.

7
Q

What can effect size facilitate with?

A

Comparison of effect across studies

8
Q

What is an estimate of effect size?

A

Correlation coefficient (r)

9
Q

What can Cohen’s D be used for?

A

To look at whether the difference between the 2 means of 2 groups is meaningful or not.

10
Q

When would you use Cohen’s D?

A

When focus is on difference between 2 means

11
Q

Cohen’s D equation

A

D = (M1-M2) / SD

12
Q

What can the SD in the Cohen’s D equation be?

A

Pooled = SD in total sample

OR

SD of control group / condition

13
Q

In what ways can we interpret the Cohen’s D size?

A

In terms of small, medium or large effect

14
Q

Small effect size for the r value and the D value

A

r = 0.1

D = 0.2

15
Q

Medium effect size for the r value and the D value

A

r = 0.3

D = 0.5

16
Q

Large effect size for the r value and the D value

A

r = 0.5

D = 0.8

17
Q

What is another way to calculate an effect size?

A

By converting a t-statistic into a Pearsons correlation coefficient (r)

18
Q

Equation to calculate effect size by converting a t-statistic to Pearsons correlation coefficient

A

r = square root of ( t^2 / t^2 + df)

19
Q

Provide reasons why its important to report effect size (3 marks)

A

Indicates whether the effect matters in the real world

Objective + standardised measure of magnitude of effect

Facilitates comparison of effect across studies

20
Q

When looking at SPSS data, what table would you look at to describe the relationship between the 2 variables?

A

Correlations table showing:

Pearsons correlation

Sig. (2 tailed)

N

i.e answer = Moderate to strong significant positive relationship, r = 0.480 and p<0.05

21
Q

How would you answer this question?

What is the regression equation for these variables?

A

Y= a + bX

Then work it out

(Look at the coefficients table)