-Random: each member has an equal chance of being selected. Statistical techniques are
used to identify what the size of the population needs to be.
-random stratified: this method is used to ensure that the same represents the population
(looks at the sample:population ratio)- get subjects from EACH SUBGROUP that exists in
the population, in correct percentages
Ex. If 1 in 3 people in a population is a babyboomer, then in a study involving 3000 people,
the same put pick out a random set of 1000 babyboomers.
Self report methods: rely on the subjects response to a set of questions to investigate the
-Alot of information can be collected easily, cost efficient manner
-Quality of the data depends on how truthful the subject was when giving the
responses (for instance person may not intentionally lie, but may give false
statements due to a faulty memory, or may be unable to be truthful because of
psychological restrictions, such as unconscious motivations)- therefore the accuracy
of the data can be a problem.
-Social desirability bias: people want to be viewed in a certain way ex. Being socially
accepted, therefore may change their answers. This affects the validity.
-Subjects may try to interpret data while being asked the questions, therefore they
will try to figure out the rationale of the study and try to respond accordingly.
Behavioural methods: measure one’s perfomance on a task (measure physiological or
psychometric response-IQ) – measuring a disability in order to assess it.
ex. Measure reading ability: ask people to rate themselves on a scale of 1-10 regading how
their reading ability is- this rely’s upon the person’s self knowledge- may be biased and not
true. However a behavioural method wouldn’t rely on asking the person, but rather gives a
test which will quantifiably measure this ability.
-allows quantitative analysis.
-If efficient measures are used, in other words if there is high validity and reliability, then
one can learn alot about a person in a short period of time (ex. 1 hour)