Transcript Trickle Down: Chlorine Dispensers and Household Water

Trickle Down: Chlorine
Dispensers and Household
Water Treatment
Michael Kremer, Harvard University and NBER
Edward Miguel, U.C. Berkeley and NBER
Sendhil Mullainathan, Harvard University and NBER
Clair Null, U.C. Berkeley
Alix Zwane, google.org
Perspectives on Impact Evaluation
March 31, 2009
Motivation
• Adoption of new technologies is often surprisingly slow in
less-developed countries
• Impact evaluations can help identify useful technologies
• Same methodologies can also help identify which
technologies are valued by constituents
• Essential to understand willingness-to-pay for scale-up
and long-run sustainability
• Important in context of larger debate about cost-sharing
for goods and services subsidized by development
agencies
– Demand effects
– Supply effects
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Household Water Treatment
• 2 million children die of diarrhea annually
• Point-of-use treatment with dilute chlorine could
drastically cut this toll, yet relatively few households use
chlorine even in areas exposed to several years of
vigorous social marketing
• In our Kenyan study area:
– 70-90% of households familiar with local brand of
chlorine
– About as many volunteer that “dirty” water is a cause
of diarrhea
– Only 5-10% of households regularly use chlorine to
treat their water
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• Dilute chlorine (similar to chlorination in
centralized water supplies in rich countries)
• Safe: developed by US. CDC & PAHO,
distributed and marketed by Population
Services International in over 20 countries
• Chlorine smell and taste is strong at first
(prevents overdosing / kids drinking straight
from bottle), fades after a few hours
• One capful disinfects 20L of water, with
residual protection against recontamination
• Wait 30 minutes after treatment before water
consumed
• 150 mL bottle treats a household’s water
supply for roughly one month
• Costs 20 KSh (US$0.30), a quarter of the daily
agricultural wage
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How to increase take-up?
• Use series of randomized evaluations to understand
factors affecting take-up:
– Price
– Persuasion
– Peer effects
– Product’s delivery system
• Iterative research process
– Use results from first phase to design strategies that
increase take-up
– Then test alternative strategies
– Future work will focus on how to make most effective
strategies sustainable and scalable
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Setting
• Demographics
– Mothers have 6 years of education
– 4 children under age 12; 1 or 2 children under age 3
• Water
– Nearest source is 8 minute walk from compound
– < 20% of HH’s meet E.P.A. drinking water standard
– < 30% boiled yesterday’s drinking water
• Hygiene & Sanitation
– > 80% have a pit latrine
– > 90% have a soap
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Phase 1: WaterGuard Intervention
• All treatment households received:
– 7 bottles of WaterGuard
– Voucher for improved clay storage pot with tap and lid
• Enumerators engaged subjects in a “directed conversation”
about water contamination and prevention strategies
– Explained dosing procedures
– Answered subjects’ questions
• 1/3 of treatment households were also given a wall
calendar and 12 coupons (redeemable monthly) for 50%
discount on WaterGuard at local shops
• 1/3 of treatment households chosen for intensive
persuasion campaign
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Study Design
• Part of larger on-going Rural Water Project
– Spring protection as source water quality improvement
• 184 communities; 7-8 households sampled at each
• Half of sampled HH’s randomly chosen for intervention
– Community-level randomization to generate exogenous variation
in exposure to WaterGuard through social networks
• “High intensity” intervention: 6 households out of 8 chosen
• “Low intensity” intervention: 2 households out of 8 chosen
• Intervention conducted after 3rd household survey
• Follow-up survey 2-7 months later
• Coupon data collected from shop-keepers
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Price and WaterGuard Use
Price=0
(Household visit)
Self-reported
Price=10
(Coupons)
Positive test
Price=20
(Social marketing)
Coupon redemption
Can price serve as a screening
mechanism?
• Some argue that price will help to screen out those who
aren’t likely to value or use the product
– Ashraf, Berry, and Shapiro (2008) in peri-urban Zambia
• We find no evidence that households who stand to
benefit most from cleaner water (i.e. those with young
children) have higher willingness to pay
– Understanding the link between water and health might be more
important
• Draws into question appropriateness of retail model
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Persuasion and Peers
• More intensive marketing messages had no effect on take-up
• Rich relationship data on all pair-wise combinations of
sampled households in each spring community
• Intervention drastically increased frequency of
conversations about WaterGuard
• Mixed evidence of take-up effects depending on outcome
– On basis of self-reported chlorine, comparison household twice as
likely to use chlorine if all of her close friends were members of
treatment group (sig. at 90% confidence)
– On basis of positive chlorine tests, no effect of social networks
• Members of the same tribe and community leaders are
especially influential on the basis of either measure
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Phase 2:
Alternative Strategies to Promote Take-up
Group 0 – Pure comparison
Group 1 – Persuasive scripts:
Group 1A – Household script only
Group 1B – Community script only
Group 1C – Household + community scripts
Group 2 – Promoters + coupon for 1 free bottle / household:
Group 2A – Flat-fee promoter
Group 2B – Incentivized promoter (paid per positive test)
Group 3 – Promoters + dispenser
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Point-of-collection Chlorine Dispenser
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Point-of-collection Chlorine Dispenser
• Drastically cuts the cost of supplying chlorine
– Approximately 25% of current individually-packaged retail cost
• Salience
• Convenience
– Walk home provides agitation and some of wait time
– Dose is more precise; doesn’t get on hands
• Habit formation
– Links water treatment to existing habits associated with water
collection
• Harnesses social network effects
– Makes decision public
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Study Design
• 88 springs randomized into community-level interventions
• Household-level script randomization at comparison &
community script springs
• Baseline surveys, interventions
– ~20 sampled household’s per spring
• Short-run follow-up (~3 weeks)
– increase sample by ~5 household’s per spring
• Medium-run follow-up (3-6 months)
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Short-run (~3 weeks):
Self-report
Positive test
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0
20
40
60
80
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Take-up by Treatment Arm
Medium-run (3-6 months):
Self-report
Positive test
0
20
40
60
80
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Take-up of Free Chlorine
Indiv. Bottles +
HH visit
Dispenser +
Promoter
(Baseline HH's)
Self-report
Dispenser +
Promoter
(Non-Baseline HH's)
Positive test
Conclusions
• Very high take-up rates of chlorine for point-of-use water
treatment when it is provided for free
– But demand is very sensitive to price
• Persuasive messages don’t seem to make much difference
beyond short-run; mixed evidence on peer effects, but
community leaders do seem important
• Local chlorine promoters were very influential, even when price
discounts ran out
– Combine potential of persuasive messages and peer effects
• Changing the way the product is delivered could be the solution:
Point-of-collection chlorine dispensers hold the most promise for
a sustainable strategy for increasing take-up at scale
– Drastically reduces cost (mainly through packaging)
– Harnesses peer effects by making use decision public
– Helps to build habits of consistent use (more convenient)
Thank you!
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