1) The study compares two interventions to promote orange-fleshed sweet potato (OFSP) adoption in Uganda to reduce vitamin A deficiency. 2) Both interventions led to a 57-64% increase in OFSP adoption and increased the share of households growing OFSP. There was no significant difference between the two models. 3) The interventions significantly increased vitamin A intake among young children, older children, and women, accounting for by increased OFSP consumption.

1. The Impact of Orange-Fleshed Sweet Potato
on Vitamin A Deficiency in Uganda:
Gender Dimensions and Asset Implications
Presented by
Sylvia Magezi, CIP
Daniel O. Gilligan, IFPRI
ILRI Campus, Nairobi Kenya
05 November 2010

2. • Compare two interventions (‘treatments’) to see which one is
more cost effective
• Model 1: Intensive two-year intervention with initial vine
distribution and subsequent trainings
• Model 2: Less intensive; identical to Model 1 in year 1, but
little activity or costs in year 2
• Evaluation design: randomized, controlled field experiment
with baseline household and nutrition survey in 2007 and an
endline surveys in 2009 (n=1,594 households)
• Assigned 84 FGs to Model 1, Model 2 or Control group at
random. Makes it possible to claim causal impacts—that
differences in outcomes are due to the project
• Survey topics: household socioeconomic and agriculture
survey; individual dietary intakes of vitamin A of young
children and their mothers
The Impact Evaluation

3. Key Findings: Adoption I
Impact on OFSP Adoption in 2009
0 20 40 60 80
Control
Model 2
Model 1
%
Cultivated OFSP
Impact: Model -
Control
M1: 64 % ***
M2: 57 % ***
• It resulted in a 57-64 % point increase in the probability of OFSP
adoption in Uganda
• There were no significant differences in these estimates across
the two different models

4. Key Findings: Adoption II
Impact on Proportion OFSP in SP Area, 2007-09
0 20 40 60 80
Control
Model 2
Model 1
%
Project End
Baseline
Impact: ΔM-ΔC
M1: 46 %***
M2: 41 %***
Δ = change
ΔM1= 47.6
ΔM2= 42.9
ΔC= 1.8
• The project increased the share of OFSP in total sweet potato
(SP) area by 41 to 46 % points in Uganda (from a base of 0%)
• Differences in impacts were no significant between Model 1 and
Model 2

5. Key Findings: Adoption III
• Past interest and experience growing sweet potato was an
important determinant of success in OFSP adoption
• Smaller farmers more likely to adopt: households in lowest
tercile of land area were 14 percentage points more likely to
adopt than those in the highest tercile
• OFSP diffusion from farmer-to-farmer is essential to
sustainability and cost-effectiveness
– half of project farmers shared OFSP vines with other farmers
– each project farmer gave OFSP vines to 1.3 farmers on
average
– 80% of these recipient farmers were first-time OFSP growers
– suggests 10,000 primary beneficiaries gave vines to another
13,000 secondary beneficiaries

6. 1%
34%
53%
66%
47%
18%
33%
19%
29%
Control
Model 2
Model 1
Orange Yellow White
110 g/d
100 g/d
118 g/d
Note: Data labels in bars show intake of sweet potato by type as a % of total sweet potato intakes.
Total sweet potato intakes (bold) represent mean intakes by all participants. Data are for a cross-
sectional group of children 6-35 months of age at the project end.
Sweet Potato Intake (by type) in grams/day for
children 6-35 months at Project End, Uganda

7. The REU intervention resulted in a significant increase in
total vitamin A intakes among young children, older
children, and women in Uganda
• The change in vitamin A intakes in the intervention
groups was accounted for by the increased intake of
vitamin A from OFSP
• OFSP contributed about 44-60% of the total vitamin A
intakes
• Impact approximately 30% higher if we only consider
adopting households
• Preliminary estimates indicate that project also
substantially reduced the prevalence of inadequate
vitamin A intakes
Key Findings: Vitamin A Intakes

8. 0 100 200 300 400 500
Control
Model 2
Model 1
Vitamin A μg RAE per day
Project End
Baseline
Change Model 2 = 169
Change Control = -55
Change Model 1 = 137
Impact:
Model 1: 192 μg RAE/day*
Model 2: 224 μg RAE/day **
Impact estimates are difference-in-difference ‘intent-to-treat’ effects on all REU participants,
including adopters and non-adopters.
Significance levels for t-statistics are: * 10% level, ** 5% level, *** 1% level.
The EAR for Vitamin A for children 1-3 years of age is 210 µg RAE/day.
Impact on Vitamin A Intakes of Children
6-35 months, Uganda

9. Impact on Vitamin A Intakes of Children
age 5-7 years, Uganda
0 100 200 300 400 500 600 700 800 900 1000 1100 1200
Control
Model 2
Model 1
Vitamin A μg RAE per day
Project End
Baseline
ΔM2= 646
ΔC= 19
ΔM1= 333
Impact: ΔM-ΔC
Model 1: 314 μg **
Model 2: 627 μg ***
Impact estimates are difference-in-difference ‘intent-to-treat’ effects on all REU participants,
including adopters and non-adopters.
Significance levels for t-statistics are: * 10% level, ** 5% level, *** 1% level.

10. Impact on Vitamin A Intakes of Women
age 18 years and older, Uganda
Impact estimates are difference-in-difference ‘intent-to-treat’ effects on all REU participants,
including adopters and non-adopters.
Significance levels for t-statistics are: * 10% level, ** 5% level, *** 1% level.
0 200 400 600 800 1000 1200 1400 1600
Control
Model 2
Model 1
Vitamin A μg RAE per day
Project End
Baseline
ΔM2= 531
ΔC= -117
ΔM1= 678
Impact: ΔM-ΔC
Model 1: 795 μg ***
Model 2: 648 μg ***

11. Model 2 is more cost effective than Model 1
• Model 2 was cheaper to implement by almost
one-third
• No difference in impact between models on rate of
adoption of OFSP, increase in vitamin A intakes or many
other key outcomes
• Plans to disseminate OFSP in the future should have an
intensive initial phase of vine distribution and limited
nutrition messages, followed by light advertising and
policies to promote OFSP crop diffusion
Differences in Costs & Impact

12. • What assets are affected?
• nutrition of children and adult women: argue to take
human capital seriously as an asset
• access to land, control over durable assets, income
• Next steps
• Third round of household survey data collection in 2011
• Qualitative and formative research
• Research topics:
• Role of social networks in OFSP technology diffusion
• how to rely on social networks to reduce cost of diffusion
• Impact of OFSP project on gender distribution of land
and durable assets
• Gender dimensions of OFSP adoption
• Gender dimensions of nutrition knowledge, risk
preferences, dietary intakes, diffusion
Gender Dimensions & Assets

13. • How do gender dimensions of control over assets,
nutrition knowledge and attitudes toward risk affect
adoption rates and intensity?
• gender-disaggregated data on ownership/control of
household assets, 2007-09
• truthfully: in 2009, retroactively asked about gender control of
assets listed in 2007
• are households in which women have more control over assets
pre-project more likely to adopt?
• does female control over assets change due to project
• detailed modules on mother’s and father’s nutrition
knowledge in both rounds
• collected information on risk preferences of spousal pairs
on subsample of data in 2007 and 2009
Intriguing Issues

14. • Hypothetical choice between safe and risky crop:
Women are somewhat less risk averse than men
Gender, Risk Attitudes and Crop Choice
0
.2.4.6.8
1
10 20 30 40 50 60 70 80 90 100
Probability of Good Rainfall %
Neutral Male Female
Nm = 94 ; Nf = 100
Information on yields only
Men vs Women
Fig. 3. Proportion Choosing Safe Crop

15. • After being given information that riskier crop is also more
healthy, women ignore production risk more than men to
gain access to healthy crop
Gender, Risk, Health and Crop Choice
0
.2.4.6.8
1
10 20 30 40 50 60 70 80 90 100
Probability of Good Rainfall %
Neutral Male Female
Nm = 88 ; Nf = 88
Information on yields and health
Men vs Women
Fig. 4. Proportion Choosing Safe Crop when Risky Crop Healthy

16. • Gender, social networks and agricultural
technology diffusion
• Social networks as institutions of exchange: farmer-to-farmer
exchange of vines more common than access through markets
• Women played a critical role in diffusion of crop to other
households: 75% of recipients of OFSP vines from project
households were women
• A detailed on-going social networks analysis will determine the
role of gender in shaping how social networks encouraged
adoption and diffusion.
• The survey round planned for 2011 will further examine the
role of gender in promoting diffusion of OFSP vines to farmers
living nearby but outside the original project locations.
Intriguing Issues