Why crime is measured in two ways

1. Nobody knows how much crime happens, so psychologists work from two measures and read them against each other.
2. Official statistics count crimes the police recorded, and self-report methods ask people directly.
3. Each misses a different slice of crime, which is why the two figures for the same year rarely match.

Official statistics

1. The main set is police recorded crime, published every three months by the Office for National Statistics.
2. Court and prison records add convictions, sentences and reoffending rates to the picture.
3. A crime enters the figures in three steps: somebody notices it, somebody reports it, and the police record it under the Home Office Counting Rules.
4. If any one of those steps fails, the offence happened but never appears in the total.

Strengths and weaknesses of official statistics

1. Strengths: the reasons psychologists still use them.
   1. They cover the whole population of England and Wales rather than a sample, so numbers for rare offences are usable.
   2. They already exist, so they cost nothing to collect and can be analysed straight away.
   3. They have been gathered in a comparable way for decades, so long-term trends and area-by-area comparisons are possible.
2. Weaknesses: the reasons the total is always too low.
   1. Crime that is never reported forms the dark figure, so the recorded total sits below the real one.
   2. People do not report because the loss feels too trivial, because they are embarrassed, because they fear reprisal, or because they expect nothing to be done.
   3. Some crimes have no obvious victim to report them, including drug possession and much fraud.
   4. Recording practice changes the figures on its own, so a tightening of the Counting Rules can raise recorded crime while actual crime is flat.

Self-report methods

1. A self-report method asks people directly, using a questionnaire or an interview, usually anonymously.
2. Victim surveys ask what has been done to you, and the Crime Survey for England and Wales interviews around 35,000 households a year about their experience over the previous 12 months.
3. Offender surveys ask what you have done, which is how Heaven (1996) measured self-reported delinquency in 282 teenagers.
4. Closed questions and rating scales turn the answers into numbers that can be compared and correlated.

Strengths and weaknesses of self-report

1. Strengths: what asking people adds.
   1. It picks up offences that were never reported to the police, so it reaches into the dark figure.
   2. Anonymity makes honest answers more likely than being interviewed by an officer would.
   3. Changes in police recording rules do not affect it, so its trend line is a better guide to whether crime is rising.
2. Weaknesses: the reasons the figures are still inaccurate.
   1. Social desirability pushes people to under-report offending they are ashamed of.
   2. Others exaggerate to look tougher, and memory slips make people misdate or forget incidents.
   3. Coverage has gaps, since a household survey misses people who are homeless or in institutions, and it cannot ask a murder victim anything.
   4. Answers cannot be checked against any objective record.

Using the two sources together

1. For offences both sources cover, the Crime Survey usually finds more crime than the police recorded, and the gap is the clearest evidence of the dark figure.
2. Where they disagree sharply, look first at whether reporting or recording changed.
3. Using both is a form of triangulation, and agreement between two very different methods is what makes a conclusion about crime levels defensible.

Turning this into marks

1. When two weaknesses of a measure are asked for, make them genuinely separate, such as unreported crime and a change in recording practice, rather than one weakness rephrased.
2. Name the source, such as police recorded crime or the Crime Survey for England and Wales, because writing that a survey was used does not secure the knowledge mark.
3. The mark most often lost is treating a recorded figure as the amount of crime that happened, when the dark figure sits outside it.