The survey sample consisted of children from mainstream, state-funded schools who were aged 5 years at the time of the survey. Examinations were conducted during the 2016/17 academic year using visual-only methods to detect signs of obvious tooth decay.
The parents of children selected for the sample were asked to give consent. Just over 3 in 10 parents (32.0%) didn’t respond, which was the main reason why children didn’t take part. A small percentage of parents (6.0%) refused consent, while 3.3% of children with consent were not at school at the time of the survey. A very small percentage (0.5%) of children with consent declined to take part on the day.
Surveys collect information from a random sample of the target population to make generalisations (reach 'findings’) about everyone within that population.
For those findings to be reliable, the sample of people should ideally contain the same mix of age, gender and regional location as the target population.
Where this isn’t the case (because some people haven’t responded, for example) analysts use statistical tools to ‘weight’ the data. Weighting rebalances the survey responses so they represent the target population more accurately. They can then be used to reach meaningful conclusions.
Deprivation scores were used to weight the sample data to more closely match the distribution of deprivation in 5 bands across the country. You can read more information about weighting in the Dental Public Health Intelligence Programme.
Confidence intervals for each ethnic group are available if you download the data.
The oral health survey is based on a sample of 5 year olds in school, rather than all 5 year olds in England. This measure makes reliable estimates of the percentage of 5 year olds in England who had no obvious tooth decay, but it’s impossible to be 100% certain of the exact percentage.
Based on the oral health survey results, it’s estimated that 76.7% of 5 year olds in mainstream schools in England in 2016/17 have no tooth decay.
It’s 95% certain, however, that somewhere between 76.4% and 77.0% of all 5 year olds in mainstream schools in England had no obvious tooth decay. In statistical terms, this is a 95% confidence interval. This means that if 100 random samples were taken, then 95 times out of 100 the estimate would fall in this range (that is, between the upper and lower confidence interval). But 5 times out of 100 it would fall outside this range.
The smaller the survey sample, the more uncertain the estimate and the wider the confidence interval. For example, fewer 5 year olds from the Chinese ethnic group responded to the survey than those from other ethnic groups, so we can be less certain about the estimate for the smaller group. This greater uncertainty is expressed by a wider confidence interval, for example of between 54.1% and 62.8% for 5 year old children of Chinese ethnicity with no obvious tooth decay in 2016/17.
Statistically significant findings have been determined where the 95% confidence intervals of an ethnic group do not overlap with the value for the group being compared.
Percentages are rounded to 1 decimal place in charts and tables, and unrounded in the data download file.
Related publicationsQuality and methodology information
Further technical information
Find further guidance and descriptions of ethnic groupings at the National Archive page on the ethnicity data standard.