Experimental Design

Question 1

Aim

Answer 1

Statement of what the research intends to find out in a research study

Question 2

Hypothesis

Answer 2

Precise & testable statement about the assumed relationship between variables. Operationalisation is a key part in making this statement testable.

Question 3

Alternative/Experimental hypothesis

Answer 3

Any hypothesis except the null hypothesis.

Question 4

Directional hypothesis

Answer 4

States the direction of the predicted difference between two conditions or two groups of participants.

Question 5

Non-directional Hypothesis

Answer 5

Predicts a difference between two conditions/groups without stating direction of the difference.

Question 6

Null Hypothesis

Answer 6

Assumption of no relationship between the variables studied.

Question 7

IV

Answer 7

Event directly MANIPULATED by experimenter in order to test its effects on the DV.

Question 8

Co-variables

Answer 8

Variables in correlation that are continuous and related.

Question 9

DV

Answer 9

Variable MEASURED by experimenter.

Question 10

Operarionalise

Answer 10

Ensuring variables are in form that can be easily tested.

Question 11

Confounding Variables

Answer 11

Confound = to cause confusion

Variable that is not the IV but varies systematically with the IV, potential changing the DV producing meaningless results.

Question 12

Extraneous Variables

Answer 12

Don’t vary systematically with IV, but may have an effect on the DV, making it difficult to detect a significant effect.

Question 13

Independent group design

Disadvantages+solution

Answer 13

P’s allocated to 2 or more groups representing different levels/conditions of the IV.

:( - researcher cannot control effects of participant variables, acting as a confounding variable.

:( - needs more p’s than repeated measures to end up with same amount of data.

P’s usually randomly allocated which distributes P variables evenly.

Question 14

Matched Pairs Design

Two disadvantages

One solution

Answer 14

Pairs of P’s matched in terms of key variables.

:( - very time consuming and hard to find matching P’s.
:( - not possible to control all P variables known to be relevant.

Conduct a pilot study to consider variables important to match.

Question 15

Repeated Measures Design

Two disadvantages

Solutions

Answer 15

Each P takes part in every condition under test.

:( - Order effect may occur which could cause practice effect (doing better) or boredom effect (doing worse).
:( - P’s may guess the aim of experiment which may alter behaviour.

• use two different tests to prevent practice effect
• cover story regarding aim of the experiment can be provided to prevent P’s guessing the real aim.

Question 16

Variable

Answer 16

Anything of relevance in a study that can vary of change