Basic principles

Question 1

Why conduct research?

Answer 1

Scientific research is relevant to clinical decision making at every level, from everyday practise to setting national guidelines

Question 2

What is a research question?

Answer 2

This provides the frame for an entire project

Everything read, experimented and discussed should relate back to it

Can be broad (like an aim) or narrow and specific (like an objective)

Question 3

What is a hypothesis?

Answer 3

A prediction of what the answer to the research question may be
- predicts the finding of a research study

This is stated at the outset of a piece of work, and once data have been collected, stat tests are used to test the validity of the hypothesis

Question 4

What is a null hypothesis?

Answer 4

H0

States there is no dependent relationship between two variables

Question 5

What is an alternative hypothesis?

Answer 5

H1

Predicts a specific and reproducible relationship between variables

Question 6

Are alternative hypotheses always directional?

Answer 6

No

They can predict in one direction but when it comes to analysing data it is good practise to check for changes in both directions in case you miss an effect

Question 7

How do we reject a null hypothesis?

Answer 7

A stats test is used to determine whether we can reject or fail to reject the hypothesis once data have been collected

Question 8

What is a p-value?

Answer 8

‘p’ is for probability and refers to the likelihood that the observed difference between groups was observed by chance

It is used to reject/fail to reject the hypothesis by comparing the probability with the significance level (a-value)

Question 9

What is an alpha (a)-value?

Answer 9

The probability of rejecting a null hypothesis when it is true

i.e. significance level of 0.05 indicates a 5% risk of concluding a difference exists when no actual difference

Question 10

How strong is the evidence against the null hypothesis for the following p-values:

a) p ≤ 0.001,
b) p ≤ 0.05,
c) p > 0.05?

Answer 10

a) very strong evidence against the null hypothesis so reject it
b) strong evidence against the null hypothesis so reject it
c) weak evidence against the null hypothesis so fail to reject it

Question 11

When would you reject the null hypothesis when comparing the p-value and a-value?

Answer 11

When the p-value is equal to or less than the a-value, we reject the null hypothesis