3j- Reporting and evaluating experimental design

Question 1

What should a method section contain?

Answer 1

Sufficient information to allow another investigator to repeat the work

Question 2

What should experimental design address?

Answer 2

The intended aim and test the hypothesis

Question 3

Under what 4 conditions can an experimental design be considered valid and allow valid conclusions to be made?

Answer 3

• the independent variable can be systematically altered
• the dependent variable can be measured
• any confounding variables should be taken into account or standardized across
  treatments
• treatment effects are compared to appropriate controls

Question 4

What should be evaluated about an experimental design?

Answer 4

Its validity and reliability

Question 5

What can be said about an experimental design that does not address the intended aim or test the hypothesis?

Answer 5

It is invalid

Question 6

When may the validity of an experiment be compromised?

Answer 6

When factors other than the independent variable influence the value of the dependent variable (confounding variable)

Question 7

What is selection bias?

Answer 7

The selection of a sample in a non-random way, so that the sample is not representative of the whole population

Question 8

What can happen when the sample size is not sufficient?

Answer 8

It may not be possible to decide without bias whether the change to the independent variable has caused an effect in the dependent variable