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Orange flesh sweet potato as a solution to vitamin A deficiency in the Indian context
Last registered on March 23, 2019


Trial Information
General Information
Orange flesh sweet potato as a solution to vitamin A deficiency in the Indian context
Initial registration date
March 19, 2019
Last updated
March 23, 2019 8:10 PM EDT
Primary Investigator
Cornell University
Other Primary Investigator(s)
Additional Trial Information
On going
Start date
End date
Secondary IDs
Promotion of Orange-Flesh Sweet Potato (OFSP) has been found to be an effective intervention to reduce vitamin A deficiency and symptoms thereof in women and children in East African communities. However, there is no such study testing the potential of OFSP as an effective intervention to reduce vitamin A deficiency of diet and associated negative health symptoms in the Indian context. Further, evidence is mixed as to the benefits of promoting OFSP using nutrition-behavior change strategies. This is a three-arm randomized trial testing the effectiveness of orange sweet potato promotion through agricultural and nutrition interventions in 15 villages in Northern Uttar Pradesh, India. The study has enrolled 1,532 consenting households to be surveyed for demographic, socioeconomic, agricultural, and dietary indicators three times over one and a half years. Five villages served as control villages and received no intervention. All ten intervention villages received 6 months of agricultural promotion of OFSP via monthly Farmer Field Schools (FSS), including one distribution of planting material at the start of the study. Five of these ten villages were randomly selected to receive 5 months of monthly nutrition information events focusing on the importance of vitamin A, the uses of OFSP in the diet, and beneficial infant and young child feeding practices. Primary outcomes are the adoption of orange sweet potato, consumption of orange sweet potato and likelihood of vitamin A adequacy of diet. This study has been approved by Cornell University IRB (Protocol Number 1708007352).

External Link(s)
Registration Citation
Merckel, Kathryn. 2019. "Orange flesh sweet potato as a solution to vitamin A deficiency in the Indian context." AEA RCT Registry. March 23. https://doi.org/10.1257/rct.3848-1.0.
Former Citation
Merckel, Kathryn. 2019. "Orange flesh sweet potato as a solution to vitamin A deficiency in the Indian context." AEA RCT Registry. March 23. http://www.socialscienceregistry.org/trials/3848/history/43945.
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Experimental Details
This study is a cluster-randomized trial designed to test the difference in primary outcomes between three intervention arms:
1) Treatment 0: Control group with no intervention
2) Treatment 1: Agricultural promotion of OFSP using Farmer Field Schools and village promotional meetings
3) Treatment 2: All activities of Treatment 1 plus an additional nutrition behavior change activities held monthly at the village level
There are five villages in each treatment arm, with control villages pre-specified due to resource constraints and remaining 10 villages randomly allocated to intervention arms (T1 and T2).
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
- household OFSP cultivation
- Frequency of consumption of OFSP (adults and children)
- Adequacy of vitamin A in the diet by women and children
- Serum retinol (pending)
Primary analysis will be done as intent-to-treat (ITT)
Primary Outcomes (explanation)
OFSP cultivation: binary variable, with a value of 1 if the household has produced OFSP in any season since the start of the project, and 0 if they have not. Responses from census surveys (Base, mid, and endline) will be cross-tabulated with ongoing agricultural record-keeping by project staff. Any households not reporting cultivation in the survey but recorded as growing by agricultural staff will be coded as growers, and any households reporting growing in the census survey but not captured by record keeping will also be coded as growers. This assessment strategy will apply for all treatment arms.
Frequency of consumption of OFSP: Respondents for the census surveys will be asked for how long OFSP was available to consume in the household, and in that time, how frequently they themselves consumed it, and how frequently it was given to children in the household.
Adequacy of vitamin A in the diet by women and children: Base, mid, and endline food frequency questionnaires (HKI) and 24-hour quantitative dietary recall will be taken for mother and reference child. 25 mother/child pairs will be chosen at random from each village, and these same will be followed longitudinally. Additionally, any producers of OFSP having a mother/child pair living in the household will be surveyed and followed longitudinally. The dietary recall will be based on common recipes collected from the villages and standardized in order to calculate average vitamin A content. VA requirements for mothers and children will be based on age, physiological status (ie lactation) and for children, frequency of breastfeeding
Serum retinol (pending): Serum retinol will be assessed in June 2019 during the harvest season of OFSP, pending permission from local authorities and contracting a local hospital or laboratory to conduct the blood draws and analysis.
Secondary Outcomes
Secondary Outcomes (end points)
- Treatment-on-treated analysis using event participation and attendance data to ascertain true exposure to intervention activities
- Sharing of vines and network analysis: impact of friend or neighbor cultivation on one's own likelihood of cultivation
- Total number of positive infant and young child feeding practices recalled
Secondary Outcomes (explanation)
S1) Effects of treatment on the treated (TOT) (identification using count of intervention events attended): Is event attendance predicted by baseline measures of socio-economic status, caste, education, or previous knowledge of OFSP or Vitamin A? (Yes/No; If yes, which characteristics?) Is cultivation and/or consumption of OFSP predicted by event attendance? (Yes/No; If yes what is the strength of association?) Was attendance at any given event more impactful than others? (Yes/No; If yes which events?)

S2) Sharing of vines and network analysis (identification based on GPS coordinates of place of residence, number of neighbors cultivating OFSP, number of friends consuming OFSP). Does cultivation or consumption of OFSP by self-reported social and agricultural contacts predict OFSP cultivation or adoption in current or subsequent season? (Yes/No; If yes, is there a critical threshold of friend/neighbor adoptipn?) Does awareness of benefits of OFSP for health predict likelihood of sharing vines with others? (Yes/No; If yes is there a critical threshold of OFSP knowledge to incite sharing, and with whom are the vines shared?)

S3) Effectiveness of nutrition intervention (both ITT and TOT) on improving infant and young child feeding (IYCF) knowledge and practices (identification based on both ITT and TOT recall of IYCF knowledge and self-reported IYCF behaviors (practices)). Subgroup analysis of attendees and non-attendees on change of knowledge and practice from baseline. Subgroup analysis of those about baseline threshold of knowledge on OFSP consumption.
Experimental Design
Experimental Design
Ten treatment villages randomly assigned to Treatment 1 (5) or Treatment 2 (5) and 5 additional villages designated as control (no treatment) as per above description of treatments. Baseline data collected before treatment commencement via census survey (all consenting households in all treatment and control villages) and maternal child food frequency and diet diversity questionnaire (30 randomly selected mother/child pairs in each treatment and control village.) All surveyed households and mother/child pairs followed longitudinally for midline and endline to determine outcomes. Villages continuously monitored for OFSP cultivation and vine sharing.

Treatments delivered over the course of 6 months via trained study staff with one agriculture (T1) and nutrition (T2) event monthly in each village following a predetermined schedule of events.

Experimental Design Details
Randomization Method
Randomization was conducted by listing treatment villages alphabetically in Excel and numbering them from 1 to 10. Then, a computer program was used to randomly draw 5 numbers without replacement from between 1 and 10. The villages matching the drawn numbers were assigned to receive the nutrition intervention.
Randomization Unit
Treatment randomized at the village level.
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
15 Villages
Sample size: planned number of observations
Observations will be at the household level, with 1500 observations at each of 3 time points assuming a 25% non-response rate
Sample size (or number of clusters) by treatment arms
5 villages per treatment arm
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
The study is powered to the primary outcomes, which are: OFSP cultivation, frequency of OFSP consumption, and serum retinol to test for VAD status. For this analysis, we use the standard β=0.80 and α=0.05, indicating an 80% chance of correctly rejecting the null hypothesis of no change, with a .05 level of significance. Because the interventions are randomized to clusters (villages) rather than to individuals, we need to account for the design effect (DE = 1 + (m-1)ICC where m is the average number of subjects per cluster) under the assumption of between-subject homogeneity within clusters. This reduction in variability within clusters results in a loss of statistical power, and therefore requires an increase in sample size to compensate. 1) OFSP cultivation will be determined by a binary indicator indicating whether the household has planted OFSP in the most recent season. In order to detect a significant difference of 15% adoption between treatment arms (Cohen’s d = .3, a relatively small effect size), we will need to survey 176 households in each treatment arm, or 35 per cluster (village). For the design effect, we expect that agricultural patterns will be heterogeneous enough within villages to make ICC negligible. With 10% loss to follow up, we aim to survey 194 households per arm, or 39 households per village. 2) Frequency of consumption of orange sweet potato will be determined by a continuous variable indicating how many times OFSP was consumed during the most recent harvest season. This variable will be surveyed for both adults in the household and children under 5 in the household. In order to detect a significant difference of 1.5 days of consumption (a medium effect size of .42), we would need 90 households in each treatment arm (18 per village). Using an estimated ICC of 0.091 for vitamin A sources in diet within rural North Indian villages (Agarwal, Awasthi, & Walter, 2005), we have DE=2.547. With 10% loss to follow-up, we must recruit 253 households per arm, or 51 households per village. 3) Serum retinol will be measured in μmol/L, with measurement <.7 μmol/L indicating deficiency. A recent study of serum retinol in UP (Neufeld, 2017) found mean (SD) maternal serum retinol (n=1284) to be .73 μmol/L (.05) and for children 6-59 months (n=1238), .65 μmol/L (.05). Using the most conservative SD for serum retinol reported in the study (.07) and an ICC estimated from Agarwal et al. (2005), we estimate a required sample size of 100 mother/child pairs per treatment group, (20 per cluster) in order to detect a .05 μmol/L difference in serum retinol. Based on these calculations, we will take the most conservative estimate to adequately power all primary outcomes. Therefore, our minimum sample size is 253 households per treatment arm. With 5 clusters in each treatment arm, we aim to recruit at least 51 households per cluster.
IRB Name
Cornell University
IRB Approval Date
IRB Approval Number
Post Trial Information
Study Withdrawal
Is the intervention completed?
Is data collection complete?
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports, Papers & Other Materials
Relevant Paper(s)