- Five enumerators have to stay for two weeks to complete the survey in one PSU. Among the five enumerators, two persons engage in collecting (diary-based) consumption data, and three persons collect nonconsumption data for two weeks.

- Since the HIES has 612 PSUs, the total number of staff weeks in the HIES is equal to 6,120 staff weeks (3,672 for nonconsumption + 2,448 for consumption parts).

- For the number of movements and days of lodging, we assumed that the enumerators for consumption and nonconsumption parts move together and can share transportation, but not lodging. So, the number of movements is independent of the number of staff in a PSU, but the days of lodging depend on staff weeks in which all staff stay in a PSU. As a result, the number of movements is 612, and the days of lodging are 42,840 (= 5 enumerators × 2 weeks × 612 PSUs × 7 days).

Table 12 confirms that the HIES costs much more than the WMS. HIES data are attractive because the consumption data are available for all households, but the required staff work weeks and days of lodging for the HIES are 20 times more than those of the WMS.

# **Costs of Collecting Consumption Data from WMS Subsamples**

Collecting consumption data from just small subsets of WMS households instead of from all households in the survey is obviously a cost-saving option. Depending on the size of subsamples, 64 and 32 PSUs were selected. Unlike the sampling of the HIES, 10 (not 20) households were chosen from each PSU. Another important assumption was that collection of consumption data was carried out separately from data collection of other modules. The first WMS data collection was conducted over one month, since most questions were not affected by seasonality. However, consumption data are likely to fluctuate in a year, so collection of the current WMS data was separated from the collection of consumption data from a WMS subsample.

**<u>Table 12: Comparison of Survey Implementation Costs</u>**

|Options|Numb<br>Total|er of PSUs<br>With<br>subsample|Staff<br>weeks|Cost<br>No. of<br>moves|Days of<br>lodging|Compar<br>Staff<br>weeks<br>(%)|ison to HIE<br>No. of<br>moves<br>(%)|S 2010<br>Days of<br>lodging<br>(%)|
|---|---|---|---|---|---|---|---|---|
|Full 2010 HIES|612|612|6,120|612|42,840|100|100|100|
|WMS only|612|NA|306|612|2,142|5|100|5|
|WMS with a<br>subsample of<br>640 households|612|64|434|676|3,038|7|110|7|
|WMS with a<br>subsample of<br>320 households|612|32|370|644|2,590|6|105|6|
|WMS with a<br>subsample of<br>640 households<br>(recall)|612|64|370|676|2,590|6|110|6|

_Source_ : Authors’ projections after consultations with BBS.

Since the number of sample households in a PSU was reduced from 20 to 10, we assumed only half the staff weeks would be needed to collect consumption data from each PSU, which implies a total of 128 staff weeks needed for collecting consumption data from 640 sample households. If the size of the subsample was set at 320, then we would need a total of 64 staff weeks. As for the number of moves, enumerators needed to move among PSUs 64 times if the size of the subsample size is 640, or just 32 times for a subsample of 320. As for the days of lodging, 896 days were needed for the subsample of 640 households, or 448 days for the subsample of 320 households.

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