Hypotheses and operationalisation By Mr Daniel Hansson Operationalisation

Hypotheses and operationalisation By Mr Daniel Hansson

Operationalisation Ø The process of making a concept measurable

Questions, operationalisation 1. How could you make intelligence measurable? 2. How could you make aggression measurable?

Experimental hypothesis Predicts differences in the measure of the dependent variable between the various conditions of the independent variable Ø 2 -tailed hypothesis: Only predict a difference Ø 1 -tailed hypothesis: Predict a particular direction in the difference (i. e. One group/condition will have a higher or lower score) Ø

Two tailed hypothesis Ø (Two tailed) There will be a difference in [the D. V. ] between [condition A of the I. V. ] and [condition B of the I. V. ] Ø (Two-tailed) There will be a difference in I. Q. Scores between male subjects and female subjects

Question, two tailed hypothesis Ø Construct a two-tailed hypothesis for Kolb’s (1999) experiment on the effect of deprived or stimulating environments on the growth of neurons in rats

One-tailed hypothesis Ø (One-tailed) There will be a decrease/increase in [the DV] in [condition A of the IV] compared to [condition B of the IV] Ø (One-tailed) There will be an increase in I. Q. Scores in female subjects than in male subjects.

Question, one tailed hypothesis Ø Construct a one- tailed hypothesis for Bandura’s bobo doll experiment

Null hypothesis Ø To be scientific every experimental hypothesis must be capable of being proven to be wrong. For this reason a null hypothesis is always proposed along with the experimental hypothesis Ø The null hypothesis states that there will be no significant difference between conditions/groups

Example, null hypotheses (Two tailed) There will be no difference in I. Q. scores between male subjects and female subjects. (One tailed) There will be no increase/decrease in I. Q. scores between male subjects and female subjects.

Question, null hypothesis Ø Construct null hypotheses for the Kolb and Bandura studies.

Accepting/rejecting null and experimental hypothesis Ø If there is a significant difference between the conditions/groups, the experimental hypothesis is accepted and the null hypothesis is rejected Ø If there is no significant difference between conditions/groups, the experimental hypothesis is rejected and the null hypothesis is accepted

Questions, one-tailed, two-tailed and null hypotheses Based on the result of the Bandura study, do you think we should reject or accept our experimental hypothesis? 2. Some studies have failed to find an effect of antidepressants on mood compared to placebo groups. For these studies, should the null hypothesis be rejected or accepted? 1.