Example of “Random Promotion” or “Encouragement Design” Rebecca Thornton University of...
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Transcript of Example of “Random Promotion” or “Encouragement Design” Rebecca Thornton University of...
Example of “Random Promotion” or
“Encouragement Design”
Rebecca ThorntonUniversity of Michigan
Randomized Evaluation of HIV Testing
Recall – Promotion Design1. Promotion was random: those who get the
promotion are just like those who didn’t2. Promotion worked: those who get the
promotion actually act on it3. Promotion doesn’t affect outcome
behavior except through the behavior itself
HIV Testing“Taking an HIV test is the single most
influential driver for behavior change” (Global Business Coalition; Richard Holbrooke)
“Making people aware of their HIV status is the only way to make them change their sexual behavior” (Bill Clinton)
55% of the total HIV/AIDS expenditure spent on testing (Mozambique)
Can we justify these financial resources being spent on HIV testing?
Conventional View #1“Once people learn their HIV status, they
will engage in safer sexual behavior”
Why might this be ambiguous for HIV positives?Altruistic towards partner …but safe sex is costly and there is no longer a
return to use protectionWhy might this be ambiguous for HIV
negatives?Increased return to safe sex …but no longer a need to act altruisticallyIndividuals may also believe that they face lower risk
Conventional View #2“It is difficult to get people to learn their HIV
status”
“I cannot accept to be tested. It is better to just live without knowing my status and see if I get sick than to know that I have AIDS in advance because then I cannot be living happily.”
“The cost of stigma is quite high, more than the bus fare to town.”
Research QuestionsHow does the demand for learning HIV
results respond to small changes in costs and benefits?
What is the impact of learning HIV results on sexual behavior?
Research DesignLimitations with existing studies and
challengesSelf-reported behavior
How might this bias the results?Selection
Who chooses to test or learn resultsWhere testing centers are locatedHow might self-selection bias the results?
We want to measure the effect of learning HIV results
Think through your exact question and plan for analysis
Among HIV positives: compare those who know their results with those who don’t
Among HIV negatives: compare those who know their results with those who don’t
Potential for selection bias?What would we randomize?
Research Design
1Got Resultsi i iY
Research DesignHow can we randomize getting HIV
results?
Incentives to learn results (subsidies of price)
Distance to results centers (subsidies of time/transport)
Malawi Panel StudyPanel study (1998, 2001, 2004)
125 rural villages in three districts – why important?
Randomly selected households (one in four)
Women and their husbands, adolescents
2004: Offered free HIV and STI tests93% accepted (2,859) 6.7% HIV Positive
Experimental DesignRandomly assigned voucher to learn HIV
resultsBetween $0-$3.00 (average=$1.04)20% received no incentive
How much were the incentives?Average daily wage: ~$1.00Smallest amount: $0.10
Why randomize by individual?
Experimental DesignResults centers
Randomly placed based on household GPS coordinates and clustered by village
Average distance = 2 km
Experimental Design
Experimental Design
Experimental Design
Percent Learning HIV Results
ReceivedNo Incentive
80%
60%
40%
20%
0Received
Some Incentive
Percent Learning HIV Results
0 0.1 0.3 0.6 1.1 1.6 2.1 2.6
Amount of Incentive (Dollars)
80%
60%
40%
20%
0
-0.2 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0
Percent Learning HIV Results
Distance from the results center
90%
80%
70%
60%
0km 1 km 2 km 3 km 4km
.6.7
.8.9
1
0 1 2 3 4Distance to VCT(KM)
Fan Regression 95% upper band 95% lower band
Experimental DesignHow do we measure the effect of learning HIV
results (going to the tent)?Need a follow-up with outcome variables – like
what?Follow-up survey (2 districts)
Gave $0.30 – why do this?Sold condoms at half retail priceOnly allowed individuals to purchase condoms from the
money they were givenDesign issues
Why have respondents purchase condoms?Why give them any money?Why cap the number of condoms allowed?
Impact of Learning HIV StatusTwo months after HIV results were available
62% reported having sex8% reported purchasing condoms
Sold condoms24% purchased condoms3.7 condoms on average
We want to measure the demand for safe sex. Why might using condom sales be problematic for this?One idea: Distinguish between those that
were sexually active and those that were not
Percent Purchasing Condoms
• HIV Negatives who had sex at Baseline
Did Not Get Results
Got Results
50%
40%
30%
20%
10%
0
Percent Purchasing Condoms
• HIV Positives who had sex at Baseline
Did Not Get Results
Got Results
50%
40%
30%
20%
10%
0
Effects after Learning HIV ResultsHIV positives with a sexual partner:
Significant increase in the likelihood of purchasing subsidized condom
But the number of condoms purchased was small – only 2 additional condoms
No effects among HIV negativesNo effects among those not having sexNo effect on likelihood of sexual activity
How could this apply to MC?Prices of MCPrizesLocation of mobile clinicsInformation – counselors, media
Other ways?
Distribution of Incentives – Day 1
Theoretical and Actual Total Distribution
0.0000
0.0500
0.1000
0.1500
0.2000
0.2500
0 30 60 90 120
150
180
210
240
270
300
Theoretical
Actual
Distribution of Incentives - overall
0.2
.4.6
.8K
ern
al D
ensi
ty
0 1 2 3Total Amount of Incentive (Dollars)
Actual Distribution Theoretical Distribution