13.07.2015 Views

A Simple Poverty Scorecard for the Philippines

A Simple Poverty Scorecard for the Philippines

A Simple Poverty Scorecard for the Philippines

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

21.64n = 0. 55 ⋅⎛ ⎞⎜ ⎟ ⋅ 0.313 ⋅ ( 1 − 0.313)= 247, which is close to <strong>the</strong> sample size of 256⎝ 0.0359 ⎠<strong>for</strong> <strong>the</strong>se parameters in Figure 9.When <strong>the</strong> sample-size factor α is less than 1.0, it means that <strong>the</strong> scorecard ismore precise than direct measurement. This occurs <strong>for</strong> all of eight poverty lines inFigure 8.Of course, <strong>the</strong> sample-size <strong>for</strong>mulas here are specific to <strong>the</strong> <strong>Philippines</strong>, itspoverty lines, its poverty rates, and this scorecard. The derivation method, however, isvalid <strong>for</strong> any poverty scorecard following <strong>the</strong> approach in this paper.In practice after July 2004 (<strong>the</strong> end date of <strong>the</strong> 2004 APIS), an organizationwould select a poverty line (say, <strong>the</strong> national line), select a desired confidence level(say, 90 percent, or z = 1.64), select a desired confidence interval (say, +/–2.0percentage points, or c = 0.02), make an assumption about pˆ (perhaps based on aprevious measurement such as <strong>the</strong> 31.4 percent national average <strong>for</strong> <strong>the</strong> 2004 APIS inFigure 2), look up α (here, 0.55 <strong>for</strong> <strong>the</strong> national line), assume that <strong>the</strong> scorecard willstill work in <strong>the</strong> future and/or <strong>for</strong> non-nationally representative sub-groups, 23 and <strong>the</strong>ncompute <strong>the</strong> required sample size. In this illustration,21.64n = 0. 55 ⋅⎛ ⎞⎜ ⎟ 0.314 ⋅ ( 1 − 0.314)= 797.⎝ 0.02 ⎠23The next sub-section discusses accuracy when applied out-of-sample and out-of-timeto <strong>the</strong> 2002 APIS. In general, per<strong>for</strong>mance after <strong>the</strong> 2004 APIS will probably resemblethat in <strong>the</strong> 2004 APIS, with some deterioration as time passes.32

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!