Local and Regional Procurement Learning Alliance

8. Market Data

TRADER SELECTION

Selecting Traders

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Selecting wholesale and retail traders to interview within each market

• Objective: track prices of 5 retailers and 5 wholesalers per commodity per market– In first period, interview up to 10 retailers and up to 10

wholesalers• There may be some attrition. Initial over-sampling means future

data can be collected by cell phone, even if one or more traders drop out

– In second period, interview five of each type of trader. The remaining five traders are in a “reserve pool”

• If one or more of these 5 traders are not available, interview from the reserve pool

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Selecting wholesale and retail traders to interview within each market

– In subsequent periods, rank traders by frequency of response.

• Interview whichever 5 traders have already responded most frequently; if one or more is unavailable, interview the next-most frequent respondent

• Return to the market to sample additional traders when it is not possible to get at least five responses from the set of ten initially interviewed

• Small or remote communities may have few traders– If fewer than ten of a trader type operate in a market,

interview (“census”) all traders of that type in that market

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First time: Number of trader informants per market per commodity

Wholesalers Retailers

Central markets in source country Up to 10 Up to 10

Central markets in recipient country Up to 10 Up to 10

Sample of source markets Up to 10 Up to 10

Sample of recipient markets Up to 10 Up to 10

Counterfactuals for source markets* Up to 10 Up to 10

Counterfactuals for recipient markets* Up to 10 Up to 10

*Pilots without an in-depth component will not need to interview traders in counterfactual markets5

Repeat interviews: Number of trader informants per market per commodity

Wholesalers Retailers

Central markets in source country 5 5

Central markets in recipient country 5 5

Sample of source markets 5 5

Sample of recipient markets 5 5

Counterfactuals for source markets* 5 5

Counterfactuals for recipient markets* 5 5

*Pilots without an in-depth component will not need to interview traders in counterfactual markets6

Randomly selecting traders to interview

• Use the following process to select traders to interview for vendors arranged around a market center:

1. Identify the approximate center of the market

2. For markets arranged along a single street: Flip a coin; you will walk to your right if you get heads; to your left if you get tails

3. For vendors arranged around a market center: Spin a pen on a flat surface; you will walk in the direction that the pen-tip points

4. Approximate the time to walk to the edge of the market from the center

5. Cut a sheet of paper into ten slips of the same length. On each slip, write a single interval: 10%, 20%, 30%, 40% … up to 100%. Put slips into a bag. Randomly select one slip. Walk this percentage-distance towards the edge of the market.

6. When you stop walking, select the first trader you reach.7

7. Ask that trader whether s/he sells any of the commodities to be monitored. If not, select a neighboring trader who does sell the commodities.

8. If a trader sells several commodities to be monitored, interview this trader about all relevant commodities sold.

9. If a wholesaler also sells commodities at retail prices, interview this trader about both wholesale and retail sales.

10. Record the respondent’s cell phone number(s) for arranging follow up visits or calls.

After completing each interview, return to the center of the market and repeat the survey process, beginning with the coin flip / pen spin, until the correct number of retailers and wholesalers per commodity is reached.

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Randomly selecting traders to interview cont.

Collecting data from traders over time

• Provide some air-time to all traders to induce them to have phones ready for follow-up surveys

• Ideally, track the same traders each period– Collect cell phone numbers– Follow up over the phone for regular price collection

• Replace unavailable trader with one from the reserve pool

• In future periods, follow up with whichever traders have responded most frequently in previous periods, drawing from reserve pool to reach 5 traders per period

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Interviewing Traders

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Eliciting commodity-specific information

• Fortified or processed commodities may not be sold directly to household or individual purchasers– It may not be possible to track retail or wholesale prices for

fortified or processed products• For blended foods, collect prices of the three main food

ingredients used to produce the fortified products, by cost– It will generally not be possible to track price series for

supplements or fortificants

• Fortified vegetable oil – If distributed vegetable oil is branded, track specific brand that

will be distributed– If fortified oil is not available in markets, track the price for

unfortified oil and note the quality difference 11

• Characteristics of commodities procured in small lots from farmer groups, cooperatives or associations may vary across (or within) groups– For example, beans varieties may vary by community, agro-

ecological zone, or individual farmer– If traders do not sell the same commodity that will be

distributed, ask traders for prices on the commodity with characteristics closest to the distributed commodity

• Showing a sample or photo of the distributed commodity can help traders identify which characteristics are most similar

– Identify the characteristics that are most common (most heavily traded) in the central market and use this in the trader surveys

• Note local names of commodities, and note which are sold in central markets, and which are not 12

Eliciting commodity-specific information

Trader interviews• For both wholesalers and retailers:

– Need to collect information on commodities identical to (or most similar to) commodities that will be distributed / monitored.

– If you are unsure whether the monitored commodity is available in this market, speak to 3-4 key informants to determine whether the exact commodity is available.

– Select only traders selling the commodities of interest.• For example, if white maize and yellow maize are sold

and you intend to distribute yellow maize, speak with vendors about yellow maize only.

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Trader interviews• The first interview will take longer than

subsequent interviews – For both wholesalers and retailers:

• Need to collect some baseline information during the first interview

– For retailers: need to establish and weigh each retailer’s standard unit of sale

• Always use your own scale to measure commodities, not the trader’s scale

• You may need to purchase commodities to measure them

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Interviewing retailers for the 1st time

• Measure the standard unit for each retailer during the first interview– Zero your scale when empty

• Ask the retailer’s usual unit or volume of sales for each commodity– Record the unit of sale by its local name– Units of sale, such as “cup” or “jerrycan”, vary

widely across traders• To decrease measurement error, need to know

precise amount each unit holds 15

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• Ask for one unit of each commodity– Weigh the unit

• If it is below two kilograms, ask the trader to give you an additional unit

– Weigh again • If the two units are still below two kilograms, ask for

an additional unit, and so on, until the scale reads at least two kilograms

– Record the number of units required to reach at least two kilograms.

– Record the scale’s exact reading of the weight

Interviewing retailers for the 1st time cont.

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• Ask and record the price per unit• Use a calculator to calculate the price per kg

or liter• In future interviews, if a retailer changes to a

different unit of sale, measure the new unit– If collecting information by phone, do not collect

price data for any commodities that have a new unit of sale until you can measure the new unit. Instead, ask a reserve pool respondent about those commodities.

Interviewing retailers for the 1st time cont.

Interviewing wholesalers for the 1st time

• A wholesale trader may sell both retail and wholesale; if so, collect both prices– On survey, note whether wholesaler is answering

questions about his/her retail or wholesale business

• For retail business, weigh unit of sale and follow previous approach for retailers

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Interviewing wholesalers for the 1st time cont.

• For wholesale business, do not weigh• Ask the wholesaler’s usual or standard unit or

volume of sales for each commodity• Record the unit of measurement by name

– Often units of measurement are 90kg or 100kg bags

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• Record the price per unit• Use a calculator to calculate the price per kg

– This is an optional step in the field and up to the discretion of each country office

• In future interviews, verify the wholesaler is still selling in his/her usual unit of sales. – Record new unit name and weight/volume, if it

changes

Interviewing wholesalers for the 1st time cont.