11 begun piloting.<sup>27</sup> The 10 program counties were the only ones out of the 90 counties in the 2003 sample that were running official NCMS pilots.<sup>28</sup> Efforts were made to ensure that the 5 nonNCMS counties were similar in relevant respects to the NCMS counties. This was done by estimating the probability of a county being selected as an NCMS pilot county, and finding (among the 2003 NHHS counties) non-pilot counties that had similar probabilities (i.e. propensity scores) to the pilot counties.<sup>29</sup> The resultant sample includes counties from all regions and all four NCMS ‘coverage modes’. However, given the opportunistic sample design, sample descriptives cannot be seen as representative for China as a whole, or for any specific province or region.

The follow-up survey successfully re-interviewed approximately 94 percent of all households, and around 87 percent of individuals from the 2003 sample **.**<sup>30</sup> There was no significant difference in the gender distributions of those originally interviewed and those not reinterviewed, but there was a difference in the age distributions, with missing individuals being more likely among the 15-34 age group. Due to missing values and other problems in the data, around 9 percent of observations were dropped in the analysis. The result is a sample of 8,476 households and 28,696 individuals in the 15 counties (5,641 households and 18,337 individuals in the 10 NCMS counties).

Table 3 reports baseline descriptive statistics for the outcomes studied for NCMS households, non-NCMS households living in the ten NCMS pilot counties, and households in living in the five non-NCMS counties. The utilization of health services is similar among all three groups, with a slight tendency towards higher rates among the NCMS households. Health spending is captured in the survey both through the household expenditure module, where households are asked how much they spent in the previous 12 months on health care, and in the specific utilization modules, where each individual in the household is asked, for each category

> 27 The survey also covered an additional 17 counties without baseline data. This was done to generate more extensive and representative descriptive data. The cross-section data are not used in this paper, because as indicated earlier, estimates based on cross-section data are likely to be biased in this context because of the influence of unobservables in the enrolment process. 28 The sample include counties from all the different coverage modes (2 inpatient only, 2 inpatient and catastrophic care, 2 inpatient and outpatient pooling, and 4 inpatient and household accounts), and from all regions (5 east, 2 center, and 3 west). 29 The probit was estimated on 2070 counties, using data from the National Bureau of Statistics county database. The variables that were significantly related to whether or not a county was selected as an NCMS pilot were: GDP per capita, the rural share of the population, and investment in fixed assets, all of which increased the likelihood of the county being selected, and the fraction of the population in middle school, which was negatively associated with being a pilot county. Variables included but which had an insignificant coefficient included: electricity use, telephone lines, fiscal revenues, government expenditures, industrial output, primary enrollment, beds in government hospitals, welfare institutions, and beds in welfare institutions.

> 30 Quality control measures in data collection and entry included extensive enumerator training, detailed review and control of five percent of sample in the field by supervisors, and double entry of data.