Psychological Investigations: the final dash…..

What do you need to know? Questionnaire How to improve the validity: Ask more precise questions Avoid loaded questions Avoid ambiguous questions Provide a wider answer scheme Use open ended questions rather than closed, forced choice answer schemes Check the results of your questionnaire against the results of a more established questionnaire on the same topic. (Craig!) This will check for CONCURRENT validity. Make people fill in the questionnaire privately.

Questionnaire How to improve/check the reliability: Use the test-retest method Test for internal reliability

Questionnaire Different ways of asking questions: Closed (Yes/No) Open ended Likert scale: state level of agreement with a statement. SA/A/NAD/D/SD Smiley faces Verbal scale Numerical scale

OBSERVATIONS How to improve reliability Video what you are observing (but note this is unethical without consent and with consent you will have….?) so others can check your results Have more than one observer so you can CHECK for inter-rater reliability Make your category/coding system very precise so someone else could easily use it.

OBSERVATIONS How to improve validity Did people know they were being watched? If so, your results may have been influenced by the Hawthorne effect. Were your categories precise enough to be accurate? Were they as vague as “some”…”lots”

Activity C What other design could you have chosen for your experiment? What would have been the advantages and disadvantages in this change of design, in relation to YOUR experiment? Be prepared to DEFINE your design.

Activity C Be prepared for a different way of measuring your DV. This could involve a change in methodology i.e. instead of asking someone about something, you could watch them. It might involve using a different rating scale It might be counting the number of correct answers after a certain time, rather than timing how long the entire task took. You have to be able to state how this change would affect the validity.

Activity C What can the mean tell us? What kind of measure is the mean? Make sure your comment on averages is clear. What kind of measure is the range? What can that tell us? No questions on the range have been asked before….

Activity D All the same stuff about changing procedure and measuring variables. Remember that correlations can NOT show cause and effect. If you state that your scatter graph or stats shows a positive/negative correlation, make sure you can clearly explain what that means in relation to YOUR experiment.