Session 4 - Statistical testing

Question 1

Purpose of statistical testing

Answer 1

To identify if any relationships between variables are statistically significant or not

Question 2

Tests try to disprove the…

Answer 2

Null hypothesis
H0
Base assumption is H0 is true
Aim to reject in favour of alternative hypothesis HA, if test is significant

Question 3

Null hypothesis

Answer 3

H0
Proposes there is no statistical significance
Claims the effect being studied does not exist

Question 4

2 sided vs 1 sided test examples
Do children from larger families have better resilience?

Answer 4

2 sided
H0 - Average resilience scores are the same
HA - Average resilience scores are different

1 sided
H0 -Average resilience scores are equal or lower
HA Average resilience scores are higher

Question 5

1 sided or 2 sided test?

Answer 5

Generally use 2 sided to allow for the possibility of results against our expectations

Question 6

p-value interpretation

Answer 6

> 0.1 little or no evidence
0.05-0.1 weak evidence (not statistically significant, fail to reject H0)
0.01-0.05 Evidence
<0.01 Strong evidence
<0.001 Very strong evidence

Question 7

Type I error (alpha)

Answer 7

Deciding against a true null hypothesis
(test statistically significant, but no true difference = H0 is true)

Question 8

Type II error (beta)

Answer 8

Failure to detect a true alternative hypothesis
(In population HA is true, there is a difference, but test is not statistically significant)

Question 8

Confidence Interval - the relationship is statistically significant if….

Answer 8

the interval does NOT include the value of the null hypothesis (difference=0)

Question 9

What to include in write up of statistical testing

Answer 9

Descriptive Summary of variables including direction and magnitude of any observed relationships
Relevant test output
Comment on statistical significance - exact p-value and quote CI of any difference
Comment on test assumptions of the test that was performed

Question 10

Inferential statistics

Answer 10

Make judgements about a population of interest using data from a sample of participants

Question 11

5 steps of conducting a statistical test

Answer 11

Research Question informs
Formulation of Hypotheses (H0, HA)
Conduct correct test on data
Test provides evidence to confirm / reject hypotheses as a probability (p)
Answer research question