Statistical Testing

Question 1

Why do we use statistical testing?

Answer 1

To find out if there is a significant difference and if the difference has occurred by chance.

Question 2

What is significance?

Answer 2

If the results can be accepted because they aren’t due to chance.

Question 3

What is the probability level?

Answer 3

• Mostly accepted ar 0.05 level
• P <- 0.05
• 95% sure results aren’t due to chance

Question 4

What does a statistical test produce?

Answer 4

A number we compare on a critical values table

Question 5

What are the 3 things we need to know for a critical value table?

Answer 5

1. Number of participants
2. One or two tailed hypotheses (direction or non- directional)
3. Significance level desired (usually 0.05 or 5%)

Question 6

If results are significant what do we accept?

Answer 6

The experimental hypothesis because there was a less than 5% probability that the results occurred but chance which means the difference was found because of the manipulation to the IV.

Question 7

If no significance is found what do we accept?

Answer 7

The null hypothesis

Question 8

Why would we use a stricter significance level e.g. 0.01 / 1%?

Answer 8

• When research involves human cost e.g. drug trials.
• When an investigation is a one-off and cant be repeated.

Question 9

What are the 3 conditions for using sign-test?

Answer 9

1. Difference rather than association
2. Repeated measures design
3. Nominal data

Question 10

Method of sign test:

Answer 10

Subtract the 2nd condition from the 1st.
1. For each ppt not whether the result is negative or positive using + or -.
2. Count the number of + and -.
3. See which is the lower of the two.
4. The lower = your S value.
5. Compare S value with the critical values table.
6. If you value is equal to or less than the CV value we can accept the result as significant.