Definitions of abnormality

Statistical infrequency

Occurs when an individual has a less common characteristic than most of the population.

How is behaviour measured in statistical infrequency?

• Behaviour can be measured as normal or abnormal according to where it is placed within a normal distribution

What can a distribution curve be used to represent?

• A distribution curve (graph) can be used to represent the proportions of a population who share a particular characteristic, e.g., IQ

Point for: Strength of statistical infrequency

• It provides clear points of comparison between people making it easy to test and to use as an objective way to compare people’s behaviour or scores against the population average (standardised: in built reliability)

Evidence for: Strength of statistical infrequency

• If person X scores 70 on an IQ test, this falls a long way below the mean average for the population 

Explanation for: Strength of statistical infrequency

• This statistically infrequent score indicates that extra help or interventions may be required for the person in question

• This makes the definition easy to test and useful as an analytical tool, because you can identify people who are very different from the norm and may need support or intervention.

Link for: Strength of statistical infrequency

• It provides a clear and measurable way of identifying abnormality meaning that different people are more likely to get consistent results, increasing its reliability

2 Limitations of statistical infrequency

• Whilst the method uses objective numerical data, deciding where to separate “normal” from “abnormal” is a subjective judgement.

• Fails to distinguish between desirable and undesirable behaviour, like high IQ and undesirable behaviour like intellectual disability, as both are statistically rare.

Evidence for: Cut off is subjective (limitatiion of statistical infrequency)

• Statistical infrequency would not recognise depression as a mental health disorder

  • Depression is estimated to affect around 280 million people across the world at any given time

Explanation for: Cut off is subjective (limitatiion of statistical infrequency)

• The high prevalence rate of depression means that it is not statistically deviant

• If depression is not statistically deviant, then statistical infrequency is not a fully valid definition of mental health

Link for: Cut off is subjective (limitation of statistical infrequency)

• This is a weakness because statistical infrequency as a definition of abnormality cannot be generalised to all mental health conditions such as depression due to how subjective the cut off point is.

Evidence for : desirable vs undesirable (limitation of statistical infrequency)

One statistically infrequent behaviour which is not necessarily undesirable or adverse is having an IQ of 175

Explanation for: desirable vs undesirable (limitation of statistical infrequency)

• A high IQ is classified as statistically infrequent yet it could not be argued that having a high IQ is undesirable or limiting in the same ways as having a low IQ would be

• This mismatch in the measure limits the usefulness of statistical infrequency

Link for: desirable vs undesirable (limitation of statistical infrequency)

This is a weakness because it brings into question the validity and usefulness of the definition. The definition, in certain instances can fail to accurately diagnose and treaty mental disorders in the real world

Social norms

The informal, unwritten rules and shared expectations that guide

acceptable behaviour within a group or society.