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Sampling example… A survey of 300 households is being conducted to assess exposure to violence-related shocks in an urban setting in the US. To achieve the level of precision required (taking into account the finite population correction coefficient) we need to survey 100 households.
Simple random sampling What is the first step??? Using the random number tables below, what would be the first household sampled (by number)? How about the second, third and fourth? Random number table 7648 2352 6959 1937 2554 6804 9098 4316 4318 2346 7276 1880 7136 9603 0163 3152 7000 2865 8357 4475 9804 0042 1106 7949 2932 9958 9582 2235 1140 1164 7841 1688 4097 8995 5030 1785 5420 0125 4953 1332 5540 6278 1584 4392 3258 1374 1617 7427
Systematic sampling… What is the sampling fraction? Using the below random numbers table and the sampling fraction, what would be the first household sampled? How about the second, third and fourth? Random number table 7648 2352 6959 1937 2554 6804 9098 4316 4318 2346 7276 1880 7136 9603 0163 3152 7000 2865 8357 4475 9804 0042 1106 7949 2932 9958 9582 2235 1140 1164 7841 1688 4097 8995 5030 1785 5420 0125 4953 1332 5540 6278 1584 4392 3258 1374 1617 7427
Cluster sampling… • We are doing a household survey in Zimbabwe. We are conducting a disproportionate sample by province. Sample size calculations (taking into account a design effect of 2) indicated that we needed to sample 900 households per province. We have decided to sample 30 clusters of 30 households. The total number of households in province 1 is 150,000. • Given that we would like to maintain a 95% confidence level and we are assuming 0.50% prevalence, what is our precision in province 1? What is our precision in province 2? • What is our sampling fraction for province 1? • What is our first and second cluster number sampled in province 1?
Random number table 7678 2352 6959 1937 2554 6804 9098 4316 4318 2346 7276 1880 7136 9603 0163 3152 7000 2865 8357 4475 9804 0042 1106 7949 2932 9958 9582 2235 1140 1164 7841 1688 4097 8995 5030 1785 5420 0125 4953 1332 5540 6278 1584 4392 3258 1374 1617 7427