National Survey of Children’s Health
Data Collection Procedures
The NSCH was conducted by telephone (landline only) in English and Spanish for the first time in 2003–2004. A second survey was fielded in 2007–2008, and a third in 2011–2012, with these rounds of the survey using both landlines and cellphones. A random-digit-dialed sample of households with children less than 18 years of age was selected from each of the 50 states and the District of Columbia. One child was randomly selected from all children in each identified household to be the subject of the survey. The respondent was a parent or guardian who knew about the child’s health and health care.
National Survey of Children's Health
National Survey of Children's Health
For the VEHSS team, NORC estimated the prevalence rate and sample size for each survey instrument selected for inclusion. We merged samples from the 2007–2008 and 2011–2012 rounds for analysis to maximize the available sample sizes for more detailed levels of stratification.
For binary response questions included in the analysis, prevalence rate was defined as the number of people who gave an affirmative response to the question divided by the total number of respondents who gave an affirmative or negative response. The result was then multiplied by 100 to obtain a percentage. For scaled responses (e.g., mild, moderate, severe), the data value was the proportion of respondents that selected one of the possible response options, and all responses should sum to 100%. We estimated upper and lower confidence intervals and the relative standard error (RSE) of the prevalence estimate using the Clopper-Pearson method. Estimates that were based on a sample size less than 30 and/or with a relative standard error greater than 30% were suppressed.
A detailed description of the analytical steps is described in the report “VEHSS Survey Analysis Plan Cdc-pdf[PDF – 480 KB]External.” Full analysis documentation is included in the “VEHSS NSCH Data Report Cdc-pdf[PDF – 592 KB]External.”
Variables Analyzed in VEHSS
NSCH 2007–2012 contains three questions related to vision. These questions were fielded intermittently from 2007 through the latest available data in 2012.
- K2Q44A- Has a doctor or other health care provider ever told you that [CHILD] had vision problems that cannot be corrected with glasses or contact lenses?
- K2Q44B- Does [CHILD] currently have vision problems?
- K2Q44C- Would you describe [his/her] vision problems as mild, moderate, or severe?
Those who responded Yes to K2Q44A were then asked K2Q44B, and those who responded Yes to K2Q44B were then asked K2Q44C.
After review of the wording of these questions, the VEHSS project partners decided to only include responses to the first question.
Overview of NSCH Variables Included in VEHSS
|VEHSS Indicator Topic||VEHSS Indicator Category||NSCH Variable Name||Years Available
|Question||Response Options Included|
|Visual Function||Difficulty Seeing with Glasses||K2Q44A||2007, 2011/2012
|Has a doctor or other health care provider ever told you that [CHILD] had vision problems that cannot be corrected with glasses or contact lenses?||1 Yes|
The analysis of NSCH for VEHSS is subject to a number of potential limitations. First, we found that 25% of the children who had a physician-diagnosed vision problem that cannot be corrected with glasses or contact lenses, apparently no longer had vision problems according to the follow-up question. We felt this was surprisingly high. Combined with what some felt was confusing wording and structure of the follow-up questions, and the high level of uncertainty in these questions when confidence intervals were based on those who actually responded to the questions, we do not have high confidence in the accuracy of the results of the follow-up questions. With this limitation, the main vision health question (K2Q44A) was the only question included in the surveillance system. In 2016, NSCH replaced the existing vision questions with one question, with similar wording to questions that are present in ACS, BRFSS and NHIS. This question will be included when NSCH is updated.
Further, our ability to stratify the NSCH data was limited. For states, we were only able to identify prevalence estimates at a single level of stratification. We included full stratification at the national level. Unlike other data sets included in VEHSS, NSCH only includes one VEHSS-defined age group, which means that full stratification of results is at the 3rd level (race*sex*diabetes).
Finally, diabetes was the only VEHSS-defined risk factor included in the survey. We were unable to identify a sufficient number of cases of diabetes to stratify results. Therefore, NSCH data does not display risk factor options in the VEHSS data visualization application.
Additional information about NSCH can be found on the Data Resource Center for Child & Adolescent HealthExternal website and the Design and Operation of the National Survey of Children’s Health, 2007 Cdc-pdf[PDF – 640 KB] Vital and Health Statistics report.
 Bramlett MD. Design and Operation of the National Survey of Children’s Health, 2011–2012 website. https://www.cdc.gov/nchs/slaits/index.htm. Accessed August 8. 2017.