Experimental Method Booklet 1

What is the difference between an aim and a hypothesis?

What is the difference between an aim and a hypothesis?

An aim is a general statement which describes the purpose of the investigation, whereas a hypothesis is a prediction of the investigation’s outcome.

What is the difference between a non-directional and a directional hypothesis?

A non-directional hypothesis states an effect will occur, whereas a directional hypothesis predicts the direction of the effect.

What is meant by ‘operationalisation’ of a variable?

Clearly defining how the variables are measured.

Describe the experimental design of independent groups/measures

Different participants are used for the 2 conditions of the IV.

Describe the experimental design of repeated measures

The same participants are used for both conditions of the IV.

Describe the experimental design of matched pairs

Different participants are used for the 2 IV conditions, but the participants are matched in terms of characteristics relevant to the study.

Give 2 advantages and 2 disadvantages of independent groups

Advantages

• No order effects

• Demand characteristics less likely

Disadvantages

• Participant variables may effect the DV

• More participants needed for this design

Give 2 advantages and 2 disadvantages of repeated measures

Advantages

• No participant variables

• Less participants needed for this design

Disadvantages

• Order effects are a problem

• Demand characteristics more likely

Give 2 advantages and 2 disadvantages of matched pairs

Advantages

• No order effects

• Demand characteristics less likely

• Participant variables reduced

Disadvantages

• Need information to match participants on

• Pre-test might be needed (expensive and time consuming)

Give 2 methods of random allocation

1. Place letters A and B in a hat and researcher selects participants one by one to each group

2. Allocate each participant a number then use a random number generator to half them in to groups

What does random allocation reduce?

Participant variables

Explain counterbalancing

The two independent groups repeat the experiment’s conditions in opposite orders to each other, reducing the impact of order effects.

Explain demand characteristics

Clues that allow participants to guess the aim of the experiment. This can make the participants change the way of their behaviour.

Define randomisation

The use of chance to reduce the effects of bias when designing materials and deciding the order of conditions.

Define standardisation

Using exactly the same formalised instructions for all participants in the study, this helps to control investigator effects.

What is the difference between extraneous and confounding variables?

Extraneous variables are control variables which may effect the DV, whereas confounding variables are control variables which have effected the DV.

Define participant variables

These are individual differences between the participants which may effect the DV (age, IQ)

Define situational variables

These are features of the situation that may effect the DV (noise, time of day)