Statistical Infrequency Flashcards
How do we display statistical data
Normal distribution curve
Statistical infrequency definition
Under this definition, abnormal behaviour is that which is rare/uncommon/unusual.
This definition relies on up to date statistics.
In statistical terms, instances of abnormality would lie at the extreme ends of a normal distribution curve. For example, low IQ is defined as intellectual
disability disorder. When looking at IQ scores, the average IQ score is 100. Scores that are significantly higher than 100 (e.g. 130), or significantly lower than 100 (e.g. 70) are quite rare or statistically infrequent.
About 68% of the population will have an IQ score between 85-115 (average)
About 95% of the population will have an IQ score between 70-130
Approximately 2% of the population will have an above average IQ score between 130 and 145 (significantly above average)
Approximately 2% of the population will have a below average IQ score between 55-70 (significantly below average)
We can display the data gained from IQ scores in a normal distribution curve
Disadvantages of statistical infrequency
- This definition fails to account for behaviour that is statistically rare but desirable. For example, someone who has an IQ above the normal average would not be seen as abnormal; on the contrary they would be very highly regarded for their intelligence
- Some psychological disorders are not statistically rare. Depression may affect 27% of elderly people (NIMH, 2001). This would make it common but that does not mean that it is not a problem.
- Many rare behaviours or characteristics have no bearing on normality or abnormality (e.g. left handedness)
- A disadvantage of statistical infrequency is that it involves labelling some people as abnormal, and this is not beneficial. A person with a low IQ of 70 might be labelled in a negative manner by other members of society, and this could have a negative effect upon them and how they view themselves. It could affect self confidence and self esteem and lead to further problems (-)
Statistical infrequency can be criticised because there seems to be a subjective cut off point between statistical infrequency (abnormality) and normality. We need to decide the dividing line between where normality and abnormality starts and ends, and this is very subjective, for instance an IQ of 70 is abnormal and statistically infrequent, but an IQ score of 71 is normal? The cut off point can be questioned. (-)
Advantages of statistical infrequency
An advantage of statistical infrequency is that to have an IQ score over 130 is just as unusual or statistically infrequent as having an IQ score below 70. However, being very intelligent with an IQ score over 130 is not an abnormality, but is actually quite positive and desirable! Just because a behaviour is statistically infrequent does not mean that the person is abnormal and requires treatment. Statistical infrequency can be a good thing (+)
2) An advantage of statistical infrequency is that judgements are based on objective, scientific and unbiased data that can help indicate abnormality and normality, (for example the IQ scores). The results from these tests can indicate whether someone needs psychological help and assistance e.g. an IQ score below 70 could indicate mental disability (+)
