How to calculate statistics of crimes?

To understand the phenomenon of crime, to analyze it, to control it, and then to prevent it, it becomes necessary to collect accurate statistics of crimes. It is also necessary to evaluate the performance of law enforcement agencies. This is a very complicated, complex, and time-consuming matter.

The attempt to count crime systematically is itself barely two centuries old. The first national criminal statistics anywhere were collected in France between 1825 and 1827, drawn from the reports of public prosecutors, and it was the Belgian astronomer Adolphe Quetelet who first used that data to argue that crimes known to the authorities and crimes that remain unknown are related by a ratio that itself shifts according to the seriousness of the offense and how diligently the justice system pursues offenders – in other words, that the raw count of recorded crime was never a direct measure of the true amount of crime taking place, only a changing fraction of it. The United States began collecting judicial statistics in New York in 1829, though it was not until 1929 that the International Association of Chiefs of Police published the Uniform Crime Report, fixing a list of seven offenses known to police – murder, forcible rape, robbery, aggravated assault, burglary, larceny, and motor vehicle theft – as the country’s standard national measure, with arson added as an eighth category in 1979. Notably, drug offenses have never been part of that list, a gap worth remembering whenever claims are made about crime rising or falling overall. England’s own national crime statistics trace to the County and Borough Police Act of 1856, the legislation that finally established professional police forces across the country and required annual reports on the serious offenses known to them.

To understand this complexity, it is necessary to clarify two or three terms. Whether the stolen property of the affected person has been returned to him or has been recovered.

Crime Rate

The increasing or decreasing pace of crimes in a particular area during a specific period is called the crime rate. Although this concept and these trends can be very useful for society, unfortunately crime statistics are highly unreliable. They are based only on those crimes that are reported to the police or those that are discovered by them. Some crimes are even deliberately ignored by the police. The reasons for not reporting crimes have already been discussed above. By some estimates, more than half of all crimes that actually occur are never reported to the police in the first place – roughly one crime reported for every two that happen – which alone should make anyone cautious about treating recorded-crime statistics as a direct headcount of criminal activity rather than a partial and shifting sample of it.

Sometimes, the number of crimes is deliberately distorted by departments in order to highlight the performance of that department or the ruling party. The American criminologist Donald Cressey once put the underlying pressure bluntly: the police are obligated to protect the reputation of their cities, and when they cannot do so efficiently through legitimate administrative means, that reputation is sometimes protected statistically instead. Researchers examining crime figures from Guangzhou, China found a concrete case of exactly this: a large apparent drop in recorded crime there in the early twenty-first century turned out not to reflect any real decline at all, but data manipulation that served, in part, to bolster the ruling party’s claim to legitimacy. Similar failures have surfaced in systems usually considered well-governed, too – a 2009 investigation by the state ombudsman in Victoria, Australia found that poor administrative systems and practices were responsible for a significant under-recording of crime, and a UK parliamentary committee went so far as to publish a report titled “Caught Red-Handed: Why We Can’t Count on Police Recorded Crime Figures,” concluding that the public should not simply trust those statistics at face value.

At times, the crime rate of one period or country is compared with that of another period or country, but such comparisons are invalid because the laws of each country are different, and even within the same country, laws keep changing.

Economists have developed the Cost of Living Index and several other indicators to guide themselves and the administration. Criminologists also wish that there were some kind of index for crime that could be useful for administrators and researchers according to their needs. However, this seems difficult at present because crime statistics cannot be relied upon.

Apart from the above reasons, there are other reasons as well for this difficulty.

First: The definitions of crime differ under different sets of laws.
Second: The sources of data are very different, such as police departments, courts, prisons, and correctional institutions.

Even the police do not record crimes in a uniform manner. Therefore, it is said that crime statistics are actually indicators of the performance of law enforcement agencies. Nevertheless, efforts are ongoing to develop such an index that could be beneficial for administrators and researchers. However, whatever data is collected is analyzed from various perspectives.

The first task is to review the total number of crimes. While analyzing them, it is examined what the nature of the crimes is. Crimes against persons include murder, violence, rape, etc., while crimes against property include robbery, theft, armed theft, burglary, etc. These crimes are divided into different categories, and it is observed in which direction criminal activities are moving. Then an investigation is made as to why this is happening and how it can be prevented.

While analyzing total crimes, it is also observed over what period these crimes occurred, and they are compared with crimes that occurred during the same period in the past so that it can be determined whether any change has occurred in criminal activities.

Crimes are also compared and contrasted on the basis of area. For example, crimes occurring in one province, district, or police station are compared with those in another or neighboring province, district, or police station, so that the overall situation becomes clear.

From crime statistics, it is also estimated how many people have been victims of criminal activities—that is, how many people were killed, how many suffered violence, how many were involved in riots, and what was the value of the property affected by criminals. Through this analysis, it is also determined how much wealth was looted in robberies, how much in burglaries, how much in thefts, and so on. This analysis also sheds useful light on criminal activities and provides good guidance to those responsible for crime prevention.

The next stage is the analysis of individuals involved in crimes. In this, it is examined how many of these offenders are previously convicted and how many times they have been punished. How many criminals are first-time offenders? What are their ages? What is their level of education, and how much potential there is for their reform? It is also observed whether they commit crimes individually or in groups. This too provides guidance to organizations working for crime prevention.

Because official statistics carry all these limitations, many countries have since developed a second, independent method of measuring crime: the victimization survey, which asks a large, representative sample of the population directly whether they have been victims of crime, regardless of whether they ever reported it to police. The United States launched its National Crime Survey in 1972, redesigned in 1991 as the National Crime Victimization Survey; England and Wales followed with what was originally called the British Crime Survey in 1982, later renamed the Crime Survey for England and Wales; and an International Crime Victims Survey has run every few years since 1989, allowing comparison across a range of countries in a way ordinary police statistics, built on different legal definitions in every jurisdiction, simply cannot support. Victimization surveys sidestep the recording problems built into police data, since they do not depend on what an officer chooses, or fails, to log. But they carry their own limitations: they cannot capture homicide, for the obvious reason that the victim is not available to be interviewed; they struggle to capture crimes without a clear individual victim, such as drug possession; and victims of repeated, ongoing abuse often cannot accurately recall how many separate incidents actually occurred, which tends to make even survey-based estimates understate the true total, sometimes by a wide margin. Even so, criminologists generally treat victimization data as the more reliable guide to long-term trends, precisely because it does not depend on the reporting and recording habits of police forces that can shift from one year, or one political administration, to the next.