generalizations are made about the population as a whole. Quantitative data are
described in terms of frequencies, means and statistically significant differences and
correlations.
Randomly allocated: subjects are randomly allocated to different conditions in order
to minimize the effects of any individual differences; for example, to ensure that
subjects who receive the drug versus the placebo versus nothing are equivalent in age
and sex. If all the subjects who received the placebo happened to be female, this would
obviously influence the results.
Repeated-measures design: this involves asking subjects to complete the same set of
measures more than once; for example, before and after reading a health information
leaflet.
Subjects: these are the individuals who are involved in the study. They may also be
referred to as participants, clients, respondents or cases.
Variable: a characteristic that can be measured (e.g. age, beliefs, fitness).
Visual analogue scale: variables such as beliefs are sometimes measured using a
100 mm line with anchor points at each end (such as not at all confident/extremely
confident). The subject is asked to place a cross on the line in the appropriate point.
Within-subjects design: this involves making comparisons within the same group of
subjects: How do subjects respond to receiving an invitation to attend a screening
programme? How does a belief about smoking relate to the subjects’ smoking
behaviour?404 HEALTH PSYCHOLOGY