research methods: Probability and significance

Question 1

What are the abbreviations for null and alternative (directional) hypotheses?

Answer 1

• Null hyothesis = H0
• Directional hypothesis = H1

Question 2

What are inferential statistics?

Answer 2

Ways of analysing data using statistical tests that allow the researcher to make conclusions about whether a hypothesis can be supported by the results

Question 3

What do inferential tests allow?

Answer 3

Inferential tests allow researchers to accept that their hypothesis and results are true

Question 4

What do inferential tests tell us?

Answer 4

If there was a significant difference or if the results occurred by chance

Question 5

What is probability?

Answer 5

A measure of the likelihood that a particular event will occur where 0 indicates statistical impossibility and 1 statistical certainty

Question 6

What is significance?

Answer 6

Tells us how sure we are that a difference or correlation exists
- a ‘significant’ result means that the researcher can reject the null hypothesis

Question 7

What happens the higher the probability?

Answer 7

The less significant the results are

Question 8

Write a flow chart of the relationship between probability and significance:

Answer 8

low probability of chance -> high significance -> accept hypothesis
high probability of chance -> low significance -> reject hypothesis

Question 9

What probability level do most psychologists use?

Answer 9

P = <0.05

Question 10

What does this probability level mean?

Answer 10

There is less than or equal to a 5% possibility that the results occurred by chance

Question 11

How do psychologists check for statistical significance?

Answer 11

By comparing the calculated value with a critical valueW

Question 12

What does the critical value tell us?

Answer 12

Whether or not we can reject the null hypothesis and accept the alternative hypothesis

Question 13

What are the three criteria of knowing which critical value to use?

Answer 13

1. One tailed or two tailed test?
2. The number of participants in the study (N). For some tests, degrees of freedom are calculated instead (df)
3. The level of significance (p value)

Question 14

What is a type 1 error?

Answer 14

The incorrect rejection of a true null hypothesis (a false positive)

Question 15

What is a type 2 error?

Answer 15

The failure to reject a false null hypothesis (a false negative)

Question 16

How can psychologists reduce the likelihood of a type 1 error?

Answer 16

By using the P=<0.01 level of significance
- increases chance of type 2 error