Methods
There are several methods for the measuring of crime. Public surveys are occasionally conducted to estimate the amount of crime that has not been reported to police. Such surveys are usually more reliable for assessing trends. However, they also have their limitations and generally don't procure statistics useful for local crime prevention, often ignore offenses against children and do not count offenders brought before the criminal justice system. Law enforcement agencies in some countries offer compilations of statistics for various types of crime. Two major methods for collecting crime data are law enforcement reports, which only reflect crimes that are reported, recorded, and not subsequently canceled; andCounting rules
Relatively few standards exist and none that permit international comparability beyond a very limited range of offences. However, many jurisdictions accept the following: * There must be a '' prima facie'' case that an offence has been committed before it is recorded. That is either police find evidence of an offence or receive a believable allegation of an offense being committed. Some jurisdictions count offending only when certain processes happen, such as an arrest is made, ticket issued, charges laid in Court or only upon securing a conviction. * Multiple reports of the same offence usually count as one offence. Some jurisdictions count each report separately, others count each victim of offending separately. * Where several offences are committed at the same time, in one act of offending, only the most serious offense is counted. Some jurisdictions record and count each and every offense separately, others count cases, or offenders, that can be prosecuted. * Where multiple offenders are involved in the same act of offending only one act is counted when counting offenses but each offender is counted when apprehended. * Offending is counted at the time it comes to the attention of a law enforcement officer. Some jurisdictions record and count offending at the time it occurs. * As "only causing pain" is counted as assault in some countries, it let higher assault rates except in Austria, Finland, Germany, the Netherlands, Portugal and Sweden. But there are exceptions, like Czech Republic and Latvia. France was the contrasting exception having a high assault ratio without counting minor assaults. Offending that is a breach of the law but for which no punishment exists is often not counted. For example: Suicide, which is technically illegal in most countries, may not be counted as a crime, although attempted suicide and assisting suicide are. Also traffic offending and other minor offending that might be dealt with by using fines rather than imprisonment, is often not counted as ''crime''. However separate statistics may be kept for this sort of offending.Surveys
Because of the difficulties in quantifying how much crime actually occurs, researchers generally take two approaches to gathering statistics about crime. However, as officers can only record crime that comes to their attention and might not record a matter as a crime if the matter is considered minor and is not perceived as a crime by the officer concerned. For example, when faced with a domestic violence dispute between a couple, a law enforcement officer may decide it is far less trouble to arrest the male party to the dispute, because the female may have children to care for, despite both parties being equally culpable for the dispute. This sort of pragmatic decisionmaking asked if they are victims of crime, without needing to provide any supporting evidence. In these surveys it is the participant's perception, or opinion, that a crime occurred, or even their understanding about what constitutes a crime that is being measured. As a consequence differing methodologies may make comparisons with other surveys difficult. One way in which, while other types of crime are under reported. These surveys also give insights as to why crime is reported, or not. The surveys show that the need to make an insurance claim, seek medical assistance, and the seriousness of an offence tend to increase the level of reporting, while the inconvenience of reporting, the involvement of intimate partners and the nature of the offending tend to decrease reporting. This allows degrees of confidence to be assigned to various crime statistics. For example: Motor vehicle thefts are generally well reported because the victim may need to make the report for an insurance claim, while domestic violence, domestic child abuse and sexual offences are frequently significantly under-reported because of the intimate relationships involved, embarrassment and other factors that make it difficult for the victim to make a report. Attempts to use victimisation surveys from different countries for international comparison had failed in the past. A standardised survey project called ''the International Crime Victims Survey'' Results from this project have been briefly discussed earlier in this article.Classification
While most jurisdictions could probably agree about what constitutes a murder, what constitutes a homicide may be more problematic, while a crime against the person could vary widely. Legislation differences often means the ingredients of offences vary between jurisdictions. The International Crime victims Survey has been done in over 70 countries to date and has been a 'de facto' standard for defining common crimes. Complete list of countries participating and the 11 defined crimes can be found at the project web site. In March 2015 the UNODC published the first version of theMeasures
More complex measures involve measuring the numbers of discrete victims and offenders as well as repeat victimisation rates and recidivism. Repeat victimisation involves measuring how often the same victim is subjected to a repeat occurrence of an offence, often by the same offender. Repetition rate measures are often used to assess the effectiveness of interventions.See also
* Crime in the United States * Crime science * Crime statistics in the United Kingdom * Dark figure of crime * List of countries by intentional homicide rate * List of countries by incarceration rate * List of countries by execution rate * Moral statistics * Questionnaire * Self report study * Statistical correlations of criminal behaviour * The International Crime Victims Survey * United States cities by crime rate *Notes
Further reading
* * * * *External links