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A Simple Poverty Scorecard for the Philippines - About the Philippines

A Simple Poverty Scorecard for the Philippines - About the Philippines

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How accurate are estimates of households’ poverty likelihoods? To measure, <strong>the</strong>scorecard is applied to 1,000 bootstrap samples of size n = 16,384 from <strong>the</strong> validationsub-sample. Bootstrapping entails: 17• Score each household in <strong>the</strong> validation sample• Draw a new bootstrap sample with replacement from <strong>the</strong> validation sample• For each score, compute <strong>the</strong> true poverty likelihood in <strong>the</strong> bootstrap sample, that is,<strong>the</strong> share of households with <strong>the</strong> score and income below a poverty line• For each score, record <strong>the</strong> difference between <strong>the</strong> estimated poverty likelihood(Figure 4) and <strong>the</strong> true poverty likelihood in <strong>the</strong> bootstrap sample• Repeat <strong>the</strong> previous three steps 1,000 times• For each score, report <strong>the</strong> average difference between estimated and true povertylikelihoods across <strong>the</strong> 1,000 bootstrap samples• For each score, report <strong>the</strong> two-sided interval containing <strong>the</strong> central 900, 950, or 990differences between estimated and true poverty likelihoodsFor each score range and <strong>for</strong> n = 16,384, Figure 7 shows <strong>the</strong> average differencebetween estimated and true poverty likelihoods as well as confidence intervals <strong>for</strong> <strong>the</strong>differences.For <strong>the</strong> national line in <strong>the</strong> validation sample, <strong>the</strong> average poverty likelihoodacross bootstrap samples <strong>for</strong> scores of 20–24 in <strong>the</strong> validation sample is too high by 1.4percentage points (Figure 7). For scores of 25–29, <strong>the</strong> estimate is too low by 1.3percentage points. 1817Efron and Tibshirani, 1993.18These differences are not zero, in spite of <strong>the</strong> estimator’s unbiasedness, because <strong>the</strong>scorecard comes from a single sample. The average difference by score would be zero ifsamples were repeatedly drawn from <strong>the</strong> population and split into sub-samples be<strong>for</strong>erepeating <strong>the</strong> entire scorecard-building process.25

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