What is the purpose of psychological measurements?
Mathematical/ statistical application measuring psychological attributes thought to be important in describing/ understanding normal/ abnormal expression of personality/ intelligence
What are the main purposes of psychometrics?
- Allows for measurement of hidden psychological attributes- indirect, normally only see expressions of attributes ie angry
- Making important decisions about individuals- psychopathology, employment, education
- Fairest/ best/ most economical method
What are limitations of psychometrics?
- Precision and accuracy
- Highly specialised
- Can be controversial
Why is the high level of specialty a limitation?
- Focus- can’t measure the whole self, have to choose a subclass ie personality, then anxiety
- Identification and minimisation of inherent errors- unknown variance- can’t capture entire space of depression, therefore errors in tests such as DASS
- Administration and interpretation- will be interpreted differently by different psychologists
Why is the high level of specialty a limitation?
- Focus- can’t measure the whole self, have to choose a subclass ie personality, then anxiety
- Identification and minimisation of inherent errors- unknown variance- can’t capture entire space of depression, therefore errors in tests such as DASS
- Administration and interpretation- will be interpreted differently by different psychologists
What is a sample?
- Process of selecting to observe some part of a target pop in order to estimate some characteristics of pop
What is a population?
Total cohort of interest
What are sample qualities?
- Representativeness
- Biasedness
- Response rate/ non-respondent/ dropouts/ volunteers
- Instability of psych attributes/ sample size
What are biases in sampling?
- Degree of systematic error present in sample
- Can create under/ over estimates of pop values
What are examples of instability in psych attributes?
- Degree of homogeneity in members of pop
- Fluctuate/ drift through lifespan, change radically
- Will come up as error
- Ie Christian-based society- don’t sample around Christmas
What are types of sampling?
-Probability (random) sampling
• Every pop unit has a known, not necessarily equal, chance of being included
•One can infer a known degree of confidence and error (bias), accurate, precise, and meaningful estimates of the characteristics of interest to the target pop
o Eg: simple (quasi-) random, systematic random, stratified, cluster
- Non- probability- do not take into account elements of chance, findings shouldnt be used to generate inferences about pop
What are the two types of scoring?
o Objective • Eg standardised questionnaires, blood tests o Subjective: assessors’ judgment • Eg vignette and projective tests o Best to use both • Don’t often • Subjective takes a long time • So tend to use objective
