UIPL 18-90 Attachment 2

 

INSTRUCTIONS FOR CHOOSING SAMPLE

  1. Determine the Skip Interval.  Divide the number of cases in the sampling frame of delayed cases (N) by the sample size (n) and round to the nearest integer to obtain. the skip interval (k).

    Examples:

    k = 60 / 30 = 2

    k = 77 / 30 = 2.56, round to 3

    k = 94 / 30 = 3.13, round to 3

  2. Determine the Random Start Number.  The table below contains a number for each SESA. Use this to select the random start number for the first case by multiplying the SESA's number by the number of cases in the sampling frame and.rounding to the nearest integer.

    AL .987   IL .596   MT .509   PR .238
    AK .576   IN .758   NE .630   RI .226
    AZ .283   IA .191   NV .560   SC .980
    AR .682   KS .350   NH .101   SD .997
    CA .685   KY .390   NJ .430   TN .397
     
    CO .954   LA .924   NM .551   TX .507
    CT .629   ME .988   NY .789   UT .765
    DE .167   MD .445   NC .796   VT .328
    DC .042   MA .316   ND .570   VA .981
    FL .284   MI .791   OH .044   WA .927
     
    GA .604   MN .353   OK .064   WV .758
    HI .178   MS .651   OR .086   WI .465
    ID .810   MO .083   PA .892   WY .577

  3. Identify Remaining Cases.  Select every kth case following the first selection (r), where k is the skip interval, until n (30) cases have been chosen. If the end of the sampling frame is reached before n cases have been selected, return to the beginning of the frame and continue the systematic selection.