Psychology C2 / PART 2

Psychology C2 / PART 2

1. Participants

   • Target populations = The group of people that the researcher is interested in. The group of people about whom generalisations can be made.
   • Sampling frames = The source material from which a sample is drawn.
   • Random sampling = A sample of participants produced by using a random technique such that every member of the target population being tested has an equal chance of being selected.
   • Opportunity sampling = A sample of participants produced by selecting people who are most easily available at the time of the study.
   • Systematic sampling = A sample obtained by selecting every nth person (where n is any number). This can be a random sample if the first person is selected using a random method; you then select every nth person after that.
   • Stratified sampling = A sample of participants produced by identifying subgroups according to their frequency in the target population. Participants are then selected randomly from the subgroups.
   • Quota sampling = Similar to a stratified sample except participants are not selected from strata using a random sampling technique.
   • Self - selected sampling = A sample of participants that relies solely on volunteers to make up the sample. Also called a self - selected sample.
   • Snpwball sampling = Relies on referrals from initial participants to generate additional participants.
   • Observational sampling techniques
     • event sampling = an observtional technique in which a count is kept of the number of times a certain behaviour (event) occurs.
     • Time sampling = an observational technique in which the observer records behaviours in a given time frame, e.g. noting what a target individual is doing every 15 seconds or 20 seconds or 1 minute. The observer may select one or more behavioural categories to tick at this time interval.

2. Experimental design

   • Independent groups = participants are allocated to two (or more) groups representing different levels of the IV. Allocation is usually done using random techniques.
   • Repeated measures = Each participant takes part in every condition under test, i.e. each level of the IV.
   • Matched pairs = pairs of participants are matched in terms of key variables such as age and IQ. One member of each pair is allocated to one of the conditions under test and the second person is allocated to the other condition.

3. Levels of measurement

   • Nominal data = a level of measurement where data are in separate categories.
   • Ordinal data = a level of measurement where data are ordered in some way.
   • Interval data = a level of measurment where units of equal intervals are used, such as when counting correct answers or using any "public" unit of measurement.
   • Ratio data =Ratio Data is defined as a quantitative data, having the same properties as interval data, with an equal and definitive ratio between each data and absolute “zero” being a treated as a point of origin. In other words, there can be no negative numerical value in ratio data.