Abhijit Banerjee
Reetamoni Das
Publication Date
October 1, 2015

Massachusetts Institute of Technology, or MIT (Banerjee, Duflo); Indian Institute of Management - Ahmedaba (Barnhardt)

"[T]he movie was effective in convincing people to adopt double-fortified salt, and to stick with it over several rounds of purchases."

This report describes a randomised control trial in Bhojpur District, Bihar, India, to shed light on how markets and information influence household decisions to adopt nutritional innovations. Specifically, it explores whether an entertaining, educational movie and an incentive for shopkeepers to push iron-fortified salt would lead to gains in the number of Indian household users.

Bihar is a large state in north India, with nearly one-third of its 103 million residents living under the poverty line as of 2012. According to the National Family Health Survey, 67% of adult women, 34% of adult men, and 78% of children under the age of 3 years suffered from some form of anaemia in 2005-06 (International Institute for Population Sciences (IIPS) and Macro International, 2008). Wendt et al. (2015) found that only 37% of pregnant women in Bihar received the recommended iron supplement in 2007-08, and only 24% of them consumed the supplement for 90 days.

Fortified foods are a potential solution for widespread iron-deficiency anaemia (IDA). In the mid 2000s, India's National Institute of Nutrition (NIN, Hyderabad) developed double-fortified salt (DFS), fortified with iron and iodine. Tata Chemicals Limited is one of the leading manufacturers of salt in India, and the researchers used their DFS, branded as "Tata Salt Plus" for the study. DFS is a relatively new product, with some characteristics that would positively influence adoption (it is clean and white, sold in a fancy packet with a trusted brand name) and some drawbacks (people are generally reluctant to try new foods, and there were some instances of food blackening early on). Moreover, the researchers found that many people did not understand the links between the product and anaemia, or between anaemia and wellbeing.

Of 400 villages in Bhojpur District, the researchers randomly assigned half to an intervention where all shopkeepers were offered the DFS (Tata Salt Plus) at 50% discount. Within treatment villages, they conducted additional interventions:

  • They commissioned a high-production-value, 26-minute edutainment movie promoting the salt's use and screened it during an intermission midway through a free showing of the classic film Nadiya Ke Par. Modeled on sitcoms and starring Bhojpuri actors (Bhojpuri is the local dialect of Hindi and has its own cinema industry), the movie tells the story of Bhim and his pregnant wife. Bhim is physically small and not very strong and wants to ensure that his son (he assumes he will have a son) will grow to be a strong man. A village nurse convinces his wife of the importance of taking iron for anaemia as a way of making sure that the child is healthy and strong, and after initial misgivings, Bhim is convinced as well. Starring prominent actors from local language cinema, the entertaining movie contrasts with the more solemn style of the traditional public health documentary. One screening was outdoors in the evening and intended for the entire village. Intended for women and children, the second showing was inside a school, daycare, medical office, or somewhere else women would feel comfortable. The movie was seen by at least one adult male in 20% of households and at least one adult female in 9.3% of households.
  • They sought to incentivise shopkeepers by randomly providing either one or all of them in a given village with higher margins to sell the product.
  • In 150 villages (in the main treatment group), they distributed hand-delivered flyers that imply informed a household about DFS and where it could be bought locally.
  • In 62 villages, they provided 7 of the 15 study households with free DFS in order to measure the impact on actual consumption and downstream biological and economic impacts of having the salt at home for free. In this paper, they use the results of free distribution on take-up as a benchmark for the effect of the other interventions.

The data come from detailed household surveys at baseline and endline. The timing of endline data collection was approximately 2 years after DFS was introduced. Purchase data come from a household salt purchase module, answered by the household head (male or female) who had the most knowledge about household purchases and assets.

The researchers estimate the impact of the different treatments using the main treatment sample of 200 villages. Without any additional intervention, just under 10% of households were currently using DFS (about 2-3 years after introduction of the product in their villages), and 20% have ever tried. When DFS is distributed for free, 54.6% of households do use it, so this probably represents an upper bound of what any kind of marketing could achieve.

For households that had to buy the salt, the movie experiment has a large impact: It increased current uptake at endline, which took place between 7 and 16 months the movie was shown, by 5.5 percentage points (57%) and "ever used" by 11.5 percentage points (22%). This is a much longer-term impact of a single exposure than what is typically evaluated. Put another way, consumption of DFS increased from 9.8% in villages where the movie was not shown to 14.4% in villages where it was shown, an increase of 50% over the mean. The effect appears to be similar for households who receive free DFS and those who do not, and for those who are in the shopkeeper experiment and those who are not. It suggests that the movie shifted the demand for the salt up, regardless of the price point: It basically changed the willingness to accept the product rather than the willingness to pay. Eight percent of households who bought DFS in the villages where the movie was shown reported that they bought this salt because it helped in fighting anaemia, as against none in other villages, and they paid a lower price on average, as advertised in the movie.

The authors also find that shopkeepers are powerful influencers of what households do. A small increase in retailer profit margins resulted in an increase in uptake at least as large as that caused by the movie screening. There is some ambiguity on how this was achieved, the researchers report. The retailers claim that they dropped the final price of the salt, albeit very little. Village households do not report such a decline and instead claim that they bought the salt because it was the only one available. "Future research should investigate the impact of providing discounts to consumers versus providing them to shopkeepers, and, more generally, examine their potential as agents of change."

These results contrast with those for the flyer distribution, which only notified households at home of where in their village fortified salt was on sale. That treatment had absolutely no impact on purchases. This suggests that both the movie and the margin treatment affected purchase because they truly changed the way households thought about the salt, as opposed to merely reminding them of its availability.


National Bureau of Economic Research (NBER) Working Paper No. 21616. DOI: 10.3386/w21616; and December 2015 NBER Digest, by Les Picker.