Experimental Method Flashcards
Aim
A general expression of what the researcher intends to investigate
Hypothesis
Operationalised
A statement of what the researcher believes to be true. It should be operationalised
ie clearly defined and measurable
Directional Hypothesis
States whether the changes are greater or lesser, positive or negative etc
Non-directional Hypothesis
Doesn’t state the direction just that there is a difference, correlation, association
Experimental Method
A researcher causes the independent variable (IV) to vary and records the effect of the IV on the dependent variable (DV)
Extraneous Variables (EV’s)
Nuisance variables that do not vary systematically with the IV. A researcher may control some of these
Confounding Variables (CV’s)
Variables that do change systematically with the IV so we cannot be sure if any observed change in the DV is due to the CV or the IV. CV’s must be controlled
Demand Characteristics
Refers to any cue from the researcher or research situation that may reveal the aim of the study
Investigator Effects
Any effect of the investigator’s behaviour on the outcome of the research (the DV)
Randomisation
The use of chance when designing investigations to control for the effects of bias
Standardisation
Using exactly the same formalised procedures for all participants in a research study
Control Groups
Control groups are used for the purpose of setting a comparison.
They act as a baseline and help to establish causation
Single Blind
A participant doesn’t know the aims of the study so that demand characteristics are reduced
Double Blind
Both participant and researcher don’t know the aims of the study to reduce demand characteristics and investigator effects
Independent Groups
Two Strengths
Two Limitations
One group do condition A and a second group do condition B.
Participants should be randomly allocated to experimental groups
+ No order effects
+ Will not guess aim
- Participant variables
- More participants
Repeated Measures
Two Strengths
Two Limitations
Same participants take part in all conditions of an experiment
The order of conditions should be counterbalanced to avoid order effects
+ Participant variables
+ Fewer participants
- Order effects are a problem
- Participants may guess aims
Counterbalancing
What happens?
An attempt to control order effects in a repeated measures design
In counterbalancing, half the participants take part in condition A then B, and the other half take part in condition B then A.
Participant Variables
May act as confounding variables in an independent groups designs because people in each condition are different. This may be the cause of the change in the DV- rather than the manipulation of the IV
Order Effects
Come about when participants are tested more than once- as in repeated measures designs. This might lead to better performance through practice, or worse performance due to boredom or fatigue
Matched Pairs
Two Strengths
Two Limitations
Two groups of participants are used but they are also related to each other by being paired on participant variable(s) that matter for the experiment
+ Participant variables
+ No order effects
- Matching is not perfect
- More participants
