Research Methods- Variables Flashcards
Variables in an experiment study
In experimental studies independent variables (IV) are the variables the researcher manipulates (changes/varies). These variations in the independent variable form the conditions of an experiment (e.g. green light vs. blue light). The researcher then measures the change/difference in another variable, known as the dependent variable (DV) (e.g. number of words recalled from a word list). In an experimental study researchers can claim to have shown a causal relationship between their manipulation of the IV and the change in measurement of the DV.
It is crucial that variables are…
operationalised
this is clearly stating exactly what the variable is and how it is to be measured.
Operationalised DV’s would include the measurement scale (eg time in seconds, Score). IV’s would clearly express each level.
Extraneous variables (EV):
Any variable (asides from the IV) that could influence the measurement of the dependant variable. This could cause an error, potentially showing a casual relationship between the IV and DV that isn’t really there, or hiding one.
Demand characteristics:
If the participant thinks they have discovered the aim, they may alter behaviour to match what they think the researcher wants. This could be due to cues from the researcher (body language/tone of voice) or the set up makes the aim obvious.
Participant variables:
In an independent groups design if there are more people with relevant characteristics, prior knowledge or skills related to the task in one condition this can result in a difference in performance between conditions unrelated to the IV.
Situational variables:
environmental factors present in one condition but not the other condition that could reasonably lead to a change in behaviour between the conditions. This could be related to temperature, noise or visual differences.
Order effects:
in a repeated measures design the fact that the participant has already completed one condition can alter behaviour in the second condition. For example, performance improvement due to practice, or performance decreases due to fatigue.
Confounding variable
A variable other than the IV that changes systematically between the levels of IV. Meaning as you change the IV you will also change the confounding variable. This then hides the IV’s true effect (or lack of an effect) on the DV as the researcher is measuring the confounding variables’ influence in addition to the IV’s.
Control
Actions taken to minimise the effect of extraneous variables on the DV.
Participant variables -
Random allocation:
Removes potential bias in assigning more participants with relevant characteristics to one condition in an independent group design. However, more participants with relevant characteristics can end up in one group due to chance.
*randomisation
is also used to assign materials used to different levels of the IV. For example randomising the individual words into separate word lists for each condition.
This is an attempt to stop all the easy to remember words appearing in one of the word lists and becoming an EV.
Participant variables - Matched pairs:
Relevant characteristics (e.g. starting anger score in a study on the effectiveness of anger management therapy) are measured before the study, and the top two participants are randomly assigned to separate groups.
Order effects - Counter-balancing:
attempts to control for (does not eliminate) order effects. This uses the ABBA format, half the participants complete condition A first and B second, and the other half of the sample start with condition B and then A. This means the order effects such as practice influence each condition equally.
Situational variables - Standardisation (procedures):
Any aspects of the environment that could (reasonably) influence the results are listed in standardised procedures.
-This list could also include a script of standardised instructions that is read in the same way to each participant. By standardising the experiment researcher ensures that each participant has the same experience aside from the variation in the IV.
Demand characteristics - single and double blind trails:
In a single-blind trail the participant does not know (is blind to) the aim of the experiment. In a double-blind trail, both the participant and the researcher who is directly testing the participant do not know the aim of the experiment.
This is an attempt to stop the researcher (consciously or unconsciously) from influencing the participants’ behaviour with their body language/ tone of voice. Standardised procedures/ scripts also reduce the likelihood of demand characteristics.
