Research Methods
Extraneous Variable
These are unwanted variables and they might influence the DV. They need
to be removed / minimised. They don’t vary with the IV, and they are easy
to identify and control. Examples of these are weather, loud noises, and
cheating etc.
Confounding Variable
These are variables that do systematically vary with the IV. They are
hidden variables, they aren’t controlled before the study, but are noticed
after as potentially having an affect on results.
The difference between the Extraneous and Confounding variables is that
confounding variables vary with the IV, and extraneous variables don’t.
Confounding variables are also hidden, but Extraneous variables aren’t.
You can write Extraneous variables as EV’s.
Demand Characteristics
These are clues / queues that may tell the participant the aim of the study,
or the investigators intentions. They might act in a way to either please the
investigator, or underperform to sabotage results.
Investigator Effects
These are any behaviours from the investigator that have an effect on the
DV. This can include; the way the study is designed, or to the selection of /
interaction with participants.
Randomisation
Extraneous Variable
These are unwanted variables and they might influence the DV. They need
to be removed / minimised. They don’t vary with the IV, and they are easy
to identify and control. Examples of these are weather, loud noises, and
cheating etc.
Confounding Variable
These are variables that do systematically vary with the IV. They are
hidden variables, they aren’t controlled before the study, but are noticed
after as potentially having an affect on results.
The difference between the Extraneous and Confounding variables is that
confounding variables vary with the IV, and extraneous variables don’t.
Confounding variables are also hidden, but Extraneous variables aren’t.
You can write Extraneous variables as EV’s.
Demand Characteristics
These are clues / queues that may tell the participant the aim of the study,
or the investigators intentions. They might act in a way to either please the
investigator, or underperform to sabotage results.
Investigator Effects
These are any behaviours from the investigator that have an effect on the
DV. This can include; the way the study is designed, or to the selection of /
interaction with participants.
Randomisation
