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Starting with the 2002 data collection, the sample allocation and design of the MEPS-IC list sample also supports a limited set of reliable private sector metropolitan-level estimates of the following:

• The percent of establishments that offer health insurance
  
• The percent of employees that enroll in health insurance plans, are eligible to enroll, and enroll when they are eligible
  
• Average premiums and employee contributions for those enrolled in employer-sponsored health insurance plans

Estimates are provided for the 20 largest metro areas nationwide and for at least one metro area within each state. The metropolitan statistical areas with a sufficient sample size to support reliable estimates with the MEPS-IC are geographically defined in the following two tables:

• Counties in metro areas within States
  
• Counties that comprise the 20 largest metro areas

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The MEPS-IC sample is selected and collection takes place at the establishment (unit) level. An establishment is generally a single physical location; a firm can consist of just a single establishment or multiple establishments.
For all sample units except 1) State governments, 2) very large local governments, and 3) those in complex multi-unit (those with nine or more establishments in the sample) private sector firms, each sample unit is initially prescreened by telephone. The purpose of this screening is to:

• determine whether or not health insurance is offered to employees at each establishment.
  
• obtain the name, title, and address of an appropriate person in each establishment to whom a MEPS-IC questionnaire will be mailed (for establishments offering health insurance).
  
• identify any establishment that no longer exists, has closed, or has merged with others.

If the employer did not offer health insurance, a brief set of questions about establishment characteristics are asked and the case is considered a complete response. This provides an inexpensive method to collect the necessary data from the large number of employers who did not offer health insurance, while minimizing the collection burden on those generally small employers.

If the employer did offer health insurance, several short questions are asked and the employer is later mailed a MEPS-IC questionnaire to obtain the remaining needed information. All establishments not reached during the screening process are also mailed questionnaires. If an establishment fails to return the initial mail questionnaire, a follow-up mailing is sent a few weeks later. Establishments that also fail to respond to the second mailing are contacted by telephone and the survey is conducted using computer-assisted telephone interviewing (CATI) technology.

For the purpose of this survey, establishments indicating that they offered health insurance to their employees must answer key information on their health insurance offerings to be considered full respondents. Callbacks are made to respondents not providing all of the key information in order to complete their questionnaires. Respondents that do not provide this key information, but are known to offer insurance, are considered partial respondents. Establishments that were not prescreened, did not return the mail questionnaires and did not respond to follow-up phone calls are classified as non-respondents. For this group, the availability of health insurance for employees at the establishment is unknown.

Data for large governments and very large private-sector firms are collected using specialized staff and forms. This is done to make the collection process simple and flexible and to reduce the burden as much as possible for these important respondents. Sometimes multiple telephone contacts and personal visits are needed to collect these data. For some of these collections, survey staff abstract data directly from company records and plan brochures if the firm insists on such methods.

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In sample surveys like the MEPS-IC, non-certainty sample establishments represent not only themselves but also other similar establishments in the survey population. Therefore, in order to produce the survey estimates and standard errors presented in the MEPS-IC tables, weights must be created for all responding establishments. A brief description of this process is provided here. During the sample design and selection process, each establishment on the frame is given a probability of selection that is dependent on its stratum. These probabilities vary among establishments and assure that the sample sizes in each stratum are equal to that required by the allocation scheme. The inverse of this probability of selection is the establishment’s base weight. The use of the base weight and the formula

provides an unbiased estimate of a total T, if there is no non-response.

Because there is non-response, respondents’ weights are adjusted to account for non-response so that these weights, when used with responding establishment data, will reduce the bias attributable to survey non-response. To accomplish this, the sample is divided into cells similar to the original sampling strata and the weights for each respondent in a specific cell are adjusted upward by the same percentage. The sum of the adjusted weights for respondents in these cells is equal to the sum of the base weights for all in-scope sampled establishments in the cell. Because it is assumed that the expected value of all responding establishments in each individual cell defined is equal to that of all the eligible respondents, use of the adjusted weights with respondents should produce the desired unbiased estimates of totals. Additional details on the enrollment and expenditure estimation process are available in MEPS Methodology Report No. 14, June 2003.

After adjustment for non-response, weights are post-stratified (Madow, Olkin, and Rubin, 1983.) using the frame of establishments in business during the last quarter of the year for which estimates would be made to produce control totals. For detailed information concerning construction of weights, see MEPS Methodology Report No. 8, November 1999. 

Although railroads are included in the sample, the 13 largest railroads are not included in the MEPS-IC tables. Employment for these railroads can not be broken down by State so their inclusion would distort results for States in which the headquarters of these railroads are located.

» Reliability of Estimates

For each table of estimates, a corresponding table of standard errors is provided. Standard errors are produced using the method of random groups. (Skinner, Holt and Smith, 1989.) The method is as follows:

• During the sequential sample selection process, each establishment selected is assigned a number corresponding to its place in the order of selection. These selection numbers are converted to 10 groups numbered 0 to 9 by assigning an establishment to the group determined by the last digit in its selection number. Thus, if the selection number were 73, the establishment would be assigned to group 3. Each group can then be thought of as a subsample similar to the full sample with each unit with a chance of selection into the subsample that was one-tenth its chance of selection into the full sample.
  
• Using subsample weights that are 10 times the nonresponse adjusted weights of the full sample, ten subsample estimates, Ei , i = 1, ...10 are made in addition to the full sample estimate, E.
  
• The standard error is calculated as:
  
                                                         

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The first level of the table numbering system is by the following categories and by year:

Within each of these categories (excluding Tables IV, IX, and X), tables are subsequently grouped by:

Tables within each of these categories are ordered based on their inter-relationships.

To clarify what each MEPS-IC table is measuring, it will be helpful to use the table (Table 1) below. For each of the MEPS-IC tables (excluding Tables IV, IX, and X), Table 1 identifies the denominator table of that table.

Examples of how to use this table to calculate approximate counts from the percentage estimates in the MEPS-IC tables are provided in the next section.

Table 1. Listing of MEPS-IC table numbers and denominators for tables

Note: Denominators are available only for tables that provide percentage estimates of counts. No “F” or “G” tables have percentage estimates of counts. Also, the “X” series of percentile distributions has no percentage estimates of counts.

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Many of the MEPS-IC tables contain percent estimates instead of count estimates. For instance, Table I.B.2 gives the percent of employees who work in establishments that offer health insurance. Table I.B.2.a gives the percent of employees who work at establishments that offer health insurance and who are eligible for health insurance. For most tables of percents, a count of the number of employees or establishments in any cell in the table can be calculated using data, for that cell, from the current table and one or more tables containing the denominator(s) for that cell.

To produce count estimates, one simply multiplies the cell values from the selected table and all of the denominators for that cell. For example, if one desired an estimate of total establishments that offer health insurance, one can find the percentage of these establishments in Table I.A.2 and determine from Table 1 on the previous page that Table I.A.1 contains the value in the denominator of this percentage.

Thus, the estimated total number of establishments that offer health insurance in 2008 is:
.562(percents must be converted to decimals) x 6,634,144 = 3,741,657.
The first number (.562) is from Table I.A.2 and the second (6,634,144) is from Table I.A.
An approximate standard error for this count estimate can be computed using this formula:

where Est(1) and Est(2) are the estimates from the two tables and Err(1) and Err(2) are the standard errors for those estimates.

= 33,035

 

For some tables, a hierarchical structure exists so more than two tables are needed to derive an approximate count. For example, look at Table I.B.2.a, the percent of employees eligible for health insurance. Table I.B.2 is listed as its denominator for Table I.B.2.a and Table I.B.1 is the denominator for Table I.B.2. The values from all three tables, I.B.1, I.B.2, and I.B.2.a must be used to derive an estimate of the count. Thus, the estimated total number of employees eligible for health insurance in 2008 is .781 x .877 x 116,141,515 = 79,549,621, with the three values coming from Tables I.B.2.a, I.B.2, and I.B.1 respectively. Basically, one must multiply by a series of denominators until one reaches a table with numbers instead of percents (the shaded areas of the Table 1 on the previous page). The standard error for this count estimate (702,489) can be computed by using a logical expansion of the standard error formula provided above.

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VIII. Major Changes to the MEPS-IC Survey by Year

Each year the MEPS-IC survey undergoes a number of changes in an effort to improve the existing survey while maintaining continuity from one year to the next. Listed below are the most significant changes that occurred in each year. In addition to the changes listed here, there were also changes to the wording and question order based on feedback from survey respondents.

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IX. References

Madow WG, Olkin I, Rubin DR. Incomplete data in sample surveys, Volume 2: Theory and bibliographies. New York: Academic Press; 1983.

Skinner CT, Holt D, Smith TMF. Analysis of complex surveys. New York: John Wiley and Sons; 1989.

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