Psychometrics

Strengths

Psychometry is based upon attempts to measure and express numerically the characteristics of behaviour in individuals.  It is therefore usually seen as an objective and scientific way of describing people and their behaviour.  

This technique, of course, provides lots of quantitative data which is easy to analyse statistically.

Psychometric tests are usually easy to administer.

Weaknesses

Constructing valid and reliable tests is very difficult.

Tests usually contain culture bias, especially intelligence tests.

Most tests will contain designer bias, in the sense that any test is biased in the direction of the author's view.

Most tests make the assumption that characteristics to be measured are fixed and unchanging, both in relation to time and also in relation to circumstance or situation. Many studies in psychology, especially social psychology, demonstrate that this is not so.  

There is the danger that the labelling of an individual as possessing a particular trait or ability will tend to encourage conformity to that trait.

The psychometric approach implies a nomothetic view of people: that is to say, a view that people are capable of being classified and measured.  The opposing view to this would argue that humans are essentially individuals and not susceptible to classification.  This is an idiographic view.

The view is frequently taken that the very fact that something is measured makes it exist as a concept.  It is often argued that 'intelligence is what intelligence tests measure'.  The concept of intelligence might not have existed at all if Binet had not set out to measure it.  Intelligence came to be defined in terms of test performance rather than as an entity itself.

One of the major dangers in psychometric testing is not so much the tests themselves, as their use by untrained or politically motivated individuals.