This analysis uses data collected through monthly submissions made using version 1.1 of the Mental Health Services Dataset (MHSDS) during the financial year 2016/17 and version 2 of MHSDS during the financial year 2017/18. This provides information for people who were detained under the Mental Health Act.
The analysis also uses Census 2011 population data for each ethnic group. In a small number of cases, a person did not have their ethnicity recorded in the dataset. This means that the ethnicity totals may not add up to the national totals.
Detentions data was incomplete in 2016/17 because not all providers of secondary mental health and learning disabilities services provided the data for all months in the year and some providers did not submit any data at all. As a result, the counts and rates shown are lower than the true figures. However, broad comparisons between ethnic groups for a given year are valid.
In 2017/18, the methodology remained the same but improved data quality means that the actual increase in detentions is likely to be less than that reported. Trend comparisons are also affected by improving data quality. Based on the providers who submitted good quality detentions data in each of the last 3 years, we estimate there was an increase in detentions of 2.4 per cent between 2016/17 and 2017/18. Broad comparisons between ethnic groups for a given year are still valid however.
Although Gypsy and Arab are identified in the population figures in the download, these groups are not separately identified in the MHSDS, so separate rates are not available for these groups. People from an Arab background do not always identify with the same broad ethnic category (they may, for example, identify as Asian or Any Other ethnic group). The way this affects the rates shown is unknown.
The broad ethnic groups used for rates of detention by broad ethnic group follow the 2001 Census groupings, which are still used in the NHS. However the 2011 census re-positions 'Chinese' from Any Other ethnic group to Asian/Asian British. This means that figures using 2011 Census categories will not be comparable with any using 2001 Census categories for 'Any Other' and 'Asian’.
The confidence intervals for the estimate of the standardised rates per 100,000 population for each ethnic group are available in the download the data section.
The number of detentions for White British people under the Mental Health Act in 2017/18 was 69.0 per 100,000 population. This is a reliable estimate based on the people detained that year, but it is not possible to be 100% certain of the true rate of detention for this population.
It’s 95% certain, however, that the rate of detention lies somewhere between 68.2 and 69.8 per 100,000 White British people. In statistical terms, this is a 95% confidence interval. This means that 95 times out of 100 the estimate would fall between the upper and lower bounds of the confidence interval. But 5 times out of 100 it would fall outside this range. The lower confidence interval is calculated by subtracting the confidence interval estimate of 0.8 from the estimate of the standardised rate of detentions. The upper confidence interval rate is calculated by adding 0.8 to the estimate.
The smaller the number of detentions, the more uncertain the estimate and the wider the confidence interval. For example, there were fewer detentions for Caribbean people than for White British people, so we can be less certain about the estimate of 254.3 per 100,000 for the Black Caribbean group. This greater uncertainty is expressed by the wider confidence interval of between 241.2 to 267.4 per 100,000 Black Caribbean people.