A range of methods have been used to minimise the chance of confounding variables.
Dependent variables used across all groups;
- receive the same instructions
- start their trial on the same day
- required to take the same placebo medication
- required to take the placebo for the same duration
- required to take the same number of placebo medication per day
- measuring all participant results using the same measurement instruments
Independent variable unique to the experimental condition;
- receive the reminder notification using the same method
- receive the same reminder notifications
Each group will experience one week in one experimental condition, and after a break of 2-4 weeks, they will be exposed to the alternative experimental condition. The study will be repeated using the same experimental condition that the first group undertook.
The purpose of this to understand if there is a marked change in performance between the same group of participants under different conditions.
The groups will have a break between condition one and two to avoid the learning effect of developing a habit of taking medication from their experience in the first experiment. The danger in the learning effect is that they may result in improved performance in the second test.
Within-subject experiments are preferable for this test because the results will be less likely to suffer from participant bias caused by individual differences.
Bias caused by participants
- Pre-screen to ensure the participants in different groups are as homogenous as possible
- no reward for participation as this may affect participant behaviour
Bias caused by experimenter behaviour
I aim to avoid bias caused by experimenter behaviour by following the recommendations of;
- randomising the placement of participants in each group
- randomising the order each group is assigned each experiment condition
- preparing the same written document with detailed instructions for participants
- being neutral, calm and patient when supervising the study
- getting everything ready before the study
- strictly following the same procedure
- recording important instructions before the experiment
- making sure all participants go through the same training process and receive the same instructions
Bias caused by environmental factors
Each participant will be asked to complete the study in their natural context of use.