Multiple Indicator Cluster Survey 2017-2018, Punjab

Essentially, by allocating specific number of sample households to each of the districts, different sampling fractions were used in each district since the size of the districts varied. For this reason, sample weights were calculated which were used in the subsequent analysis of the survey data.

The major component of the sampling weight is the reciprocal of the sampling probabilities employed in selecting the number of sample households in that particular sampling stratum (h) and PSU (i).

The term fhi is the sampling fraction for the i-th sample PSU in the h-th stratum and defined as the product of the probabilities of selection at every stage in each sampling stratum.

Where pshi is the probability of selection of the sampling unit at stage s for the i-th sample PSU in the h-th sampling stratum.

The number of households in each enumeration block (PSU) from the frame was used for the first stage selection and the updated number of households in the enumeration block from the actual household listing is generally different. Consequently, individual overall probabilities of selection for households in each sample enumeration block (cluster) were calculated.

After the completion of fieldwork, response rates were calculated for each sampling stratum. These were used to adjust the sample weights calculated for each cluster.

The non-response adjustment factors for the individual women and under-5 questionnaires were applied to the adjusted household weights. Numbers of eligible women and under-5 children were obtained from the list of household members in the Household Questionnaire for households where interviews were completed.

The weights for the questionnaire for individual men were calculated in a similar way. In this case, the number of eligible men in the list of household members in all the MICS sample households in the stratum was used as the numerator of the non-response adjustment factor, while the number of completed questionnaires for men in the stratum was obtained from the 50% subsample of households. Therefore, this adjustment factor includes an implicit subsampling weighting factor of 2 in addition to the adjustment for the non-response to the individual questionnaire for men.

In the case of the questionnaire for children age 5-17 years, in each sample household, one child was randomly selected from all the children in this age group recorded in the list of household members. The household weight for the children age 5-17 years is first adjusted based on the response rate for this questionnaire at the stratum level. Once this adjusted household weight is normalised as described below, it is multiplied by the number of children age 5-17 years recorded in the list of household members. Therefore, the weights for the individual children age 5-17 years will vary by sample household.

For the water quality testing (both in household and at source) a subsample of 3 households was selected from the 20 MICS sample households in each sample cluster. Therefore, the basic (unadjusted) household weight would be multiplied by the inverse of this subsampling rate.

Since the response rate may be different for the water quality testing for home consumption and at the source, the basic weights for each were adjusted separately for non-response at the stratum level.

The MICS Punjab, 2017-18 full (raw) weights for the households were calculated by multiplying the inverse of the probabilities of selection by the non-response adjustment factor for each stratum. These weights were then standardised (or normalised), one purpose of which is to make the weighted sum of the interviewed sample units equal to the total sample size at the national level. Normalisation is achieved by dividing the full sample weights (adjusted for nonresponse) by the average of these weights across all households at the national level. This is performed by multiplying the sample weights by a constant factor equal to the unweighted number of households at the national level divided by the weighted total number of households (using the full sample weights adjusted for non-response). A similar standardization procedure was followed in obtaining standardised weights for the individual women, men, under-5 questionnaires and water quality testing. Adjusted (normalised) household weights varied between 0.297817 and 3.101398 in the 2,692 sample enumeration areas (clusters).