Methodological Issues in the Evaluation of the National Long Term Care Demonstration. IV. SPECIFIC METHODOLOGICAL ISSUES EXAMINED


The randomized design, large samples, and straightforward estimation methodology eliminate the major reasons for questioning the evaluation results. However, despite these strengths a number of methodological issues arose that could cast doubt on the validity of the estimates obtained. The issues include:

  • Actual equivalence of the treatment and control groups
  • Comparability of the baseline data for treatment and control groups
  • Sample attrition
  • Validity of pooling observations across sites and models
  • Differences between early and late cohorts of sample members
  • Inappropriateness of regression procedure for some outcomes
  • Effect of use of proxy respondents on impact estimates

Each of these issues was examined early in the analysis to determine whether it would lead to biased or distorted estimates of channeling impacts, and, when necessary, procedures were developed to avoid such distortions. For the major issues--comparability of the baseline data and attrition bias--separate reports were prepared (Brown and Mossel, 1984; Brown et al., 1986) that describe the analyses in detail. For the other issues, internal memoranda document the analyses. The results from these investigations are summarized below. The documents from which they were drawn are available from the author upon request.

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