Limitations of the study involved using a restricted sample, among others.
39 Estimation using a restricted sample (one large district: Charlotte-Mecklenburg) looking at only within-district transfers yielded qualitatively similar results.
To control for endogeneity in auditor's selection, the model is estimated using a restricted sample of firms, which hired, at least, one non-sanctioned auditor during the sample period and one sanctioned auditor in the pre-inspection period.
While the results of the re-survey suggest that provider timing assignment errors in the principal provider sample were not common, all regression models using the principal provider sample were re-estimated using a restricted sample of providers with a confirmed practice affiliation for the pre- and post-MRI years.
To control for endogeneity in auditor's selection, the model is estimated using a restricted sample of firms, which hired, at least, one sanctioned auditor in the pre-inspection period and one non-sanctioned auditor in any year of the sample period.
Our study differs from others in the literature in that, by including almost all the inhabitants in the Basque Country, it avoids the potential bias that could arise by only using a restricted sample of the population.
We also compared the relative risk of death from CVD between non-HDL-C and LDL-C, using a restricted sample of adults who attended the morning session of a mobile examination center, had fasted at least 8 hours, and had a valid LDL-C value (n = 366).
Second, a restricted sample of 16 settlements was used for a more in-depth diachronic analysis of how settlements combined different means of security over several decades.
In addition, our results remain qualitatively the same when applying a regression discontinuity design to a restricted sample firms ranked around the Russell 1000/2000 cut-off.
Small sample sizes and a restricted sampling area could have limited the conclusiveness of these findings.
