Experiments Flashcards
(25 cards)
IV.
The variable that the experimenter manipulates. The changes are called ‘conditions’.
DV.
The variable that is measured. It will change depending on what the experimenter does to the IV.
Manipulation of variables and measurement of the resultant…
…change helps to establish a ‘cause and effect’ relationship between 2 or more events.
Hypotheses.
All experiments are testing a hypothesis. This is a statement that specifies what is going to be tested and how it will be measured.
Experimental hypothesis.
Predicts the effect of the IV on the DV. E.g there will be a difference between…
In order for the hypothesis to be tested it needs…
…to be ‘operationalised’ (made testable).
The Null Hypothesis.
States that there will be no effect of the IV on the DV. E.g, there will be no difference between…
One tailed hypothesis.
Predicts the direction in which results are expected to occur.
Two tailed hypothesis.
Will simply state that there is some kind of difference between the two events.
Reliability in experiments.
Refers to whether a measurement device is consistent. A measurement is said to be reliable if the measurement can produce similar results of used again in similar circumstances.
Internal reliability.
Refers to whether the procedure is the same within the experiment. E.g, for every participant or between conditions.
External reliability.
Refers to whether the procedure is the same between experimenters. E.g, when the study is replicated at a later date will it give the same/similar results assuming nothing has changed.
Validity.
Refers to whether an experiment really measure what it claims to.
Internal validity.
Refers to whether a test measures what it claims to measure.
Test validity.
Refers to whether a test measures the effect of the IV on the DV.
Extraneous variable.
Factors other than the IV that could cause the DV to change. E.g, light, noise, temperature, etc.
The experimenter needs to attempt to control these…
…EV’s so he/she knows they have not caused the changes in the DV.
(Experimental design)
Repeated measures.
Compares the performance of participants in one condition with their own performance in another condition.
Repeated measures.
+
Individual differences of participants are removed since each participant is compared against him/herself.
Repeated measures.
-
People may do better or worse on the second condition, e.g, they may become bored.
Repeated measures.
–
Participants may be able to guess the aims of the study, which may cause demand characteristics.
Independent measures.
Compares the performance of different participants in each of the experimental conditions.
Independent measures.
+
Participants are less likely to guess the aims of the study.
Independent measures.
-
Differences in performance between 2 groups may be due to individual differences (you may be measuring that rather than the effects of IV) (validity).
