There is a strong interest in the crime rate of mentally ill persons. There is also fact check article. There are some reports that people with mental illnesses tend not to be prejudiced because the crime rate is low. The messages are different, but both are based on government data. Depending on how you extract the data, the meaning depends on how you calculate it.

● Government statistics use 'incidence' instead of 'crime rate'

The prosecution annually publishes a book called Crime Analysis. Official crime statistics of the country. 'Crime Analysis' has an item called 'Mental Disability Offender'. Mentally handicapped criminals' criminal record and motive, arrest and detention, and disposition results. However, the "Crime rate" column is not listed. People who are not mentally ill do not have the same crime rate. The 'crime rate' is the expression used by the press and the public, and the government booklet uses statistics called 'accrued rain'.

Crime 'incidence' is the number of cases per 100,000 population. "2017 Crime Analysis" has criminal data for 2016. The crime incurred in 2016 is 3,884.8. There were 3,884 crimes per 100,000 people. There is a number in 2017, and there is a reason for using data in 2016. However, this incidence includes not only criminal offenses, but also property crimes such as fraud and bribery.

● Calculating the incidence of mental illness crime "...
What is the crime rate of a mentally ill person? The prosecution does not disclose 'the incidence of crimes of mentally ill persons' separately. To calculate the incidence, you need to know the total number of population, and you can convert it to 'per 100,000 people'. The prosecution does not produce the number of people with mental illness. Also, after calculating crime rates for mental illnesses, there may be a protest of discrimination against certain groups if the state is open to the public. Prosecutors are disclosing the total number of mental illnesses who committed crimes every year.

The total number of mentally disabled offenders in 2016 is 8,343. This is not the number of crimes, but the number of criminals with mental disabilities. The basis of the numbers is the 'statistical statistics of suspects', which is a table in which the investigating agency makes one copy for one suspect. So even if one mental patient has committed two or three crimes, it will be counted as one. So, in 2016, there could be more than 8,343 cases of mental illness crime.

Considering that the actual number of crimes can be higher, let's start with 8,343 cases. The number of people with mental illness is surveyed by the Ministry of Health and Welfare. I do not do it myself, but I do an in-depth investigation every five years with an outside medical service. 2016 data is up-to-date. Twenty-four national medical personnel participated in this report. It is a method of interviewing 5,100 people over 18 years old.

According to the report, the total number of people aged 18 or older who have experienced psychiatric disorders in 2016 (excluding alcohol and nicotine use disorders) is 2,870,000. It is this number that many media use to calculate crime rates for mentally ill persons. So the following comparison is made.

▷ Crime incidence in 2016 (the number of crimes per 100,000 people)
- Total crime incidence 3,884.8 (Prosecutor, '2017 Crime Analysis' figures)
- Crime incidence of mental illness 290.7 (calculated by the prosecution, Ministry of Health and Welfare)

● Uncertain data ... There is no statistics on 'crime rate'. Reports of low rates of crime for people with mental illness are based on this comparison. It is pointed out that the risk of mental illness is only a prejudice of the public. But you can not be 100% sure of your data. As I mentioned earlier, the crime of mental illness is calculated not by the 'thing' but by the 'person', and there is no statistic that the government officially announces the crime data of the mental disorder by the same standard. There is no statistics on 'crime rate'.

● Multiple loopholes in the calculation of crime rates for mentally ill persons

The total number of mentally ill 2,870,000 people is part of the population used to calculate the total crime incidence. The data overlaps. There is an intersection. The prosecutor's office calculated the crime incidence in 2016 by taking the population of the National Statistical Office on December 31, 2016, and it is said that the number of people with mental illness is 2.87 million. Since there is no statistical calculation that divides the two categories clearly as if they were cut with a knife, the comparison is inevitably less accurate.

In addition, the prosecution uses the "total population" number of the Republic of Korea to calculate the crime incidence, but it differs when the press calculates the crime rate for mentally ill persons. As you have seen, I use the data of the Ministry of Health and Welfare. 2.87 million mentally ill people are only 18 years old or older. Compare two numbers, one counting the population as the "total population" and the other counting "18+", which is not an accurate comparison.

As a result, compared to only 3,884 and 290, the total crime incidence is 13 times higher than the mental illness group. The crime rate for people with mental illness is not particularly high. There is no clear basis for high crime rates for people with mental illness.

Until now, it was the total number of crimes. You can count the cases that the media deals with. Murder, fire, and robbery are classified by the prosecution as "violent crime (violent crime)." In 2016, the incidence of violent crime (violent crime) was 63.8 cases per 100,000 people. If we estimate this incidence only for people with mental illness, about 29.5 per 100,000 population comes out. Just as the incidence of total crime was low, the incidence of violent crime (maltreatment) also tends to be low.

● When we look at the percentage of violent crimes (violent crimes) among all crimes ...

However, it is remarkable that the proportion of violent crimes (abuse) among the crimes of mentally ill persons in 2016 is high. Of the 8,343 criminals of all mental illnesses, 847 and 10.2% were violent crimes. Like a murder and arson incident in Pearl (Related article: The armed robbery after residents of apartment fire ... 5 deaths, 13 injuries) . On the other hand, in the case of non-mental patients, the number of violent crimes (abuse) was 1.6% in the total number of crimes. If there is a public opinion that a mentally ill person is 'dangerous', it is probably due to the imprint of this 10.2% incident.

▷ Percentage of violent crimes (violent crimes) among all crimes in 2016 (calculated by the prosecution "2017 crime analysis")
- Non-mental patients 1.64%
- mental patients 10.15%
● "Mental disorder" classification of investigation agency ... Leading to the limits of statistics

However, there are loopholes in this number as well. I will return to the basics of statistics. Mental disorder is the 'number' of crime. This number is collected by the prosecution. It collects data that the prosecution investigates and investigates by the Police-Special Judicial Police. No judgment is directly reflected in the process. In the process of investigation, police officers digitize and document certain suspects as mental disorders. In detail, it divides into 'mental disorder', 'mental retardation', and 'other mental disorder'. This classification is not mandatory, and there is no manual.

I can not believe 100% of the judgments about suspect mental disorders. Even in this case, the police received 112 reports in the past seven times, but did not confirm the psychiatric history. In such cases, the prosecutor's "crime analysis" is classified as a general crime, not a mental disorder crime.

When the police classify a mental disorder, they refer to a doctor's medical certificate, a reference statement, and records of taking mental disorders, but there is a limit. That limit leads to the limits of statistics, which became the basis of "crime analysis". It is a contradiction to report that the crime rate of mental illness is high or low, or 100% certain, based on mental disorder crime data produced by the police, criticizing the police as having limitations in identifying the psychiatric history of the suspect. I can only refer to crime prevention.

(Source: Park Kyu Ri)