NCMP 2006/07 frequently asked questions

Based on the questions we are asked the most, we compiled these FAQs.

  • what is the National Child Measurement Programme?

    Established in 2005, the National Child Measurement Programme weighs and measures primary school children aged 4- 5 (reception) and 10 -11 (year 6). The programme has been produced using one of the largest databases of its kind in the world.

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  • why are these data being collected?

    The National Child Measurement Programme was set up in line with the Government's strategy to tackle obesity and to:

    * inform local planning and delivery of services for children

    * gather population-level data to allow analysis of trends in growth patterns and obesity

    * increase public and professional understanding of weight issues in children and be a vehicle for engaging with children and families about healthy lifestyles and weight issues.

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  • who participated?

    For 2006/07, 80 per cent (876,416) of all eligible pupils from reception (aged 4-5) and year 6 (aged 10-11) were measured. The school children involved were from non-specialist, maintained state schools in England (local primary schools).

    Private, special, foundation special, non-maintained special, independent, pupil referral units etc were excluded because local PCTs do not routinely work with these schools.

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  • what are the main findings?

    in reception, almost one in four of the children measured was either overweight or obese. In year 6, this rate was nearly one in three:

    * the prevalence of obesity is significantly higher in boys than in girls in both age groups

    * the percentage of children who are overweight is only slightly higher in year 6 than in reception

    * the percentage of children who are overweight is similar for boys and girls in year 6: in reception, this rate is slightly higher for boys than for girls

    * obesity prevalence is significantly higher than the national average in the North East, West Midlands and London SHAs for both school years

    * obesity prevalence is significantly below the national average in the South East Coast, South Central, South West and East of England SHAs for children in both school years, as well as for year 6 children in the East Midlands SHA

    * obesity prevalence is higher in urban areas than in rural areas

    * there is a strong positive relationship between deprivation and obesity prevalence for children in reception and year 6

    When interpreting the results, it is important to consider the possible effects of participation rate on prevalence rates. Since the participation rate was less than 100 per cent, data will be missing for certain children

    If these missing data were atypical, results could be biased. For example, if children with higher BMI scores opted out of being measured, overweight and obese prevalence would be underestimated

    Analysis later in the report shows that year 6 prevalence of obese and overweight may be slightly underestimated but that results for reception children are likely to be more robust.

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  • does this mean obesity is increasing?

    Because of the low response in 2005/06, it has not been possible to compare the results between the two years. However, year-on-year analysis should be possible in the future when participation rates have stabilised and changes in prevalence due to changes in participation rates can be discounted.

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  • how many children were weighed and measured for the 2006/07 National Child Measurement Programme ?

    For 2006/07, 80 per cent (876,416) of all eligible pupils from reception (aged 4-5) and year 6 combined were measured.

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  • how were the children measured?

    Children's heights and weights were measured and used to calculate BMI or Body Mass Index. The measurement process was overseen by trained healthcare professionals in schools.

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  • what do we mean by overweight and obese?

    Defining children as overweight or obese is a complex process, given that their height and weight change at the same time. An individual's BMI is calculated by dividing their weight (expressed in kilograms) by the square of their height (expressed in metres).

    For adults, defining overweight or obese is straightforward given that they are assumed to have stopped growing: individuals with BMI between 25 and 29.9 are considered to be overweight, while those with a BMI greater than or equal to 30 are considered to be obese.

    Given that a child's height and weight both change at the same time, it is necessary to take into account their age and sex when considering their BMI. In accordance with NICE guidelines, we apply Cole's LMS Method to standardise children's BMI using the national standardised growth charts.

    A child can be defined as overweight and obese by looking at their standardised BMI (p-score): where this is between the 85 and 95 percentile, they are considered to be overweight; where it is greater than the 95 percentile they are considered to be obese.

    Further detail can be found in the report or by referring to Cole's LMS Method: Growth monitoring with the British 1990 growth reference. Cole Arch Dis Child.1997; 76: 47-49.

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  • which are the areas with the worst obesity problem?

    Obesity prevalence is significantly higher than the national average in the North East, West Midlands and London SHAs for both school years.

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  • which areas have the lowest obesity levels? is obesity worse in boys or girls?

    Obesity prevalence is significantly below the national average in the South East Coast, South Central, South West and East of England SHAs for children in both school years, as well as for year 6 children in the East Midlands SHA.

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  • how do the results for obesity differ between year 6 and reception?

    The prevalence of obesity is significantly higher in year 6 than in reception.

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  • what other data are there to compare with these results?

    The best comparison figures available to compare with the National Child Measurement Programme (NCMP) findings are child obesity data from the Health Survey for England (HSE). The HSE is a series of sample-based surveys focusing on a range of health indicators including obesity in children.

    Section 3.11 of the report shows that the findings of the NCMP and HSE are very close for the majority of measures, with headline prevalence rates that are not statistically significantly different for each study (except for the obesity rate for boys in reception).

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  • why do National Child Measurement Programme figures differ from the Health Survey for England data?

    Most of the figures from the two studies are very close. There is only one exception, namely the obesity prevalence for boys in reception. Any differences in the figures could be explained by differences in the survey design and analytical techniques applied in each of the studies, including:

    * HSE collects data from children in private households whereas the National Child Measurement Programme (NCMP) collects data from children in schools. Consequently HSE will exclude data from children living in institutions (for example, care homes) and NCMP will exclude data from children not attending school

    * NCMP excludes data from children in independent and special schools; NCMP is not a sample-based design. Either collection could include an element of bias if children who did not participate were atypical (for example, if they had higher BMI)

    * The HSE sample of valid heights and weights for the relevant age groups is considerably smaller than in the NCMP sample (1,693 versus 876,416) and is therefore, at disaggregated levels, more susceptible to natural random variation.

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  • the National Child Measurement Programme also took place in the 2005/06 school year. Why haven't you compared the 2006/07 data with the first year's data?

    The response rate in 2005/06 was approximately 48 per cent, compared with 80 per cent in 2006/07. Because of the low response in 2005/06, it has not been possible to compare the results between the two years.

    However, year-on-year analysis should be possible in the future when participation rates have stabilised and changes in prevalence due to changes in participation rates can be discounted.

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  • do the figures relate to England or the UK?

    The report looks at children in England only.

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  • can we compare with other countries?

    Different countries use different methods for defining overweight and obese children. International comparisons would be very difficult and are outside of the scope of this report.

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  • was it compulsory for children to participate in the programme? we know that only 80 per cent of eligible children were measured. How do we know these results are meaningful?

    Participation in the programme was not compulsory, but non-participation was on an opt-out basis only. Before the programme started, PCTs wrote to the parents and carers of all children eligible for measurement to inform them of the work and to give them the opportunity to opt their children out.

    Children were not made to participate if they did not want to.

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  • what about underweight children? Why don't you show the numbers of underweight children identified from the National Child Measurement Programme?

    There is no agreed definition of underweight, so the report does not attempt to analyse this.

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  • if PCTs could add or remove schools and alter numbers of children in each school, doesn't this mean that they could lower the numbers to make it look like they've measured a greater percentage than they really have?

    The Information Centre (IC) performed a number of validation checks on the data to ensure that the findings were as accurate as they could be. If, for example, one PCT removed a school from its results but the school was not subsequently recorded by another PCT, the school was added back in to the original PCT's list.

    The overall figures on numbers of eligible pupils provided by PCTs were compared with those provided by DCSF, and any variations were queried by the IC and agreed with the relevant PCT where necessary.

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  • how were the National Child Measurement Programme data collected?

    Primary Care Trusts (PCTs) collected data on children's height and weight from all schools within their area. The data were submitted to The Information Centre using the National Child Measurement Programme data collection tool and all of the returns were collated and validated centrally.

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  • what is the National Child Measurement Programme data collection tool?

    The Information Centre (IC) collected the data using the National Child Measurement Programme (NCMP) data collection tool, one of the largest databases of its kind in the world. Populating this data warehouse involved:

    * the development of a secure data collection tool and supporting secure data warehouse

    * storing anonymised data relating to children's height, weight and location

    * generating aggregate information data for geographically defined populations other than school catchments areas. The NCMP data collection tool comprised of three elements:

    1. the development of a Microsoft Excel based tool to capture the necessary variables on-site, with inbuilt validation of data to maximise the potential of collecting robust and accurate data including a feedback of summary data

    2. a web site to enable NHS Primary Care Trusts to securely submit data to The IC

    3. the development of a data warehouse to capture and analyse the captured data.

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  • how do we know the information is secure?

    PCT role
    Every year the Department of Health (DH) and the Department for Children, Schools and Families provide guidance to PCTs and schools which emphasises how to undertake the exercise. The guidance also clearly points out that:

    * the privacy and dignity of the child must be safeguarded at all times and the measurement is to be done sensitively in a private setting

    * the height and weight information must be gathered by health professionals with minimal physical contact

    * PCTs will take steps to ensure that parents receive a letter explaining the purpose of the programme, and provide them with the opportunity to withdraw their child from it

    Information Centre role
    The National Child Measurement Programme (NCMP) data capture tool is held by The Information Centre (IC). All IC staff must attend an information governance training session on the Knowledge Skills Framework which covers information security and confidentiality.

    Guidance leaflets for all staff which promote the IC's compliance with Data Protection and Information Security are available and can be requested from The IC Contact Centre on 0845 3006046 or enquiries@ic.nhs.uk.

    * although IC will not have access to any patient identifiable information, there are robust information security measurements in place to ensure that data is held and accessed securely

    * before loading the data electronically, the measurements process is overseen by trained healthcare professionals and is not shared with school staff or pupils. PCTs upload the data electronically to the NCMP, developed and maintained by the IC

    * when the data is uploaded to the NCMP database the data is anonymised by removing or converting all identifiable data: the name of the child is automatically removed; the postcode is converted to lower Super Output Area; the date of birth is converted to age in months

    * individual children's results will not be shared with school staff or other pupils and suppression and disclosure controls will be implemented when the dataset and publication is released. When data is published, small numbers that could allow individual children to be identified will be suppressed

    For example, at Super Output Area level and even at PCT level, if a small number between 1 and 5 appears in any specific data cell, that number will be replaced by an X; so to will any corresponding total relating to that number

    * local authorities and other delivery partners are given an anonymous, aggregated report only, and do not have access to the raw data. Any organisation wishing to obtain access to the anonymous national dataset requires the approval from both the IC and the DH.

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  • what future changes are planned for the National Child Measurement Programme?

    The Information Centre will repeat the National Child Measurement Programme data collection for 2008/2009.

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