types of experiments - RM

Internal reliability

The extent the experiment was conducted consistently

External validity

The extent to which the study is consistent overtime

Internal validity

Whether or not we can say for certain that the IV has caused the effect seen in the DV

External validity

The extent to which results can be generalised

Lab experiments strength (highly controlled)

Cause and effect can be established, without the effects of extraneous variables, so you can be more certain the IV caused the effect in the DV

Lab experiment strength (reliability)

Due to high control and standardised procedures the experiment can be replicated

Weakness of lab experiment (ecological validity)

Due to high levels of control, you lose realism. Findings are less credible and can’t be applied beyong the setting of experiment

A weakness of lab experiment (DC)

Participants more likely to guess the aim of the study and change their behaviour accordingly

5 key features of lab experiments

Conducted in highly controlled environment

Experimenter deliberately manipulates the IV across conditions

Experimenter measures the dependent variable

Experimenter controls extraneous variables

Procedure and instructions are standardised

4 key features of field experiments

Conducted in a more natural environment

Experimenter deliberately manipulates the IV across conditions

Experimenter measures DV

Experimenter controls some of the extraneous variables

Strength of field experiment (ecological validity)

More realistic the lab experiments as the study is being conducted in a real setting, we are able to generalise the findings to real life

Strength of field experiment (DC)

Participants less likely to guess the aim of the study due to less control and can’t change their behaviour accordingly

Weakness of field experiments (cause & effect)

Due to a more realistic setting there will be less control so there could be more extraneous variables so you can’t be certain the changes in DV are soley due to IV

Weakness of field experiment (reliability)

Lack of control and difficulty having fully standardised procedure makes the experiment less replicable so the consistency of findings can't be verified

3 key features of natural/quasi experiments

Experimenter has no control over the IV

Experimenter measures the DV

Experimenter has no control over extraneous variables

Strength of natural/quasi experiments (ecological validity)

Researchers are not manipulating the IVs, they are naturally occuring so can be generalised to real life so the studies may be more useful

Strength of natural/quasi experiments (DC)

Researcher is not manipulating anything so participants are less likely to guess their aims and change their behaviour accordingly, so high internal validity

Weakness of natural/quasi experiments (lack of control)

More difficult to establish cause snd effect since you aren’t manipulating and controlling variables, so yo can’t be certain the IV is causing the DV due to extraneous variable, so internal validity may be lower

Weakness of nautral/quasi experiments (reliability)

We are relying on naturally occuring evenrts and not manipulating the variables ourselves, it is difficult to replicate the studies so the consistency of the findings can't be checked