I have spent much of the last few months thinking about how the data we collect influences the conclusions we draw. Today, I’ve been reading a draft of a paper called “Remembrance of Things Past: The Impact of Recall Periods on Reported Morbidity and Health Seeking Behavior” by Jishnu Das, Jeff Hammer and Carolina Sánchez-Paramo that provided a nice illustration of the importance of how data is collected.
The authors find that conclusions drawn about the health and health seeking behavior of families in New Delhi, India change depending on the “recall period” they use in their surveys. A “recall period” is the amount time that goes in the blank of the following question: “Have you been sick in the last ___?” Many surveys use either “the last week” or “the last month.”
In particular, people report fewer acute illnesses when they are asked to reflect on their health in the past month than if they are interviewed weekly for a month. They also report fewer doctors’ visits, fewer incidences of self-medication, and less expenditure on health care (when expenditure is capped at 200 rupees per month, the approximate amount of two days wages for a day laborer). So, looking at monthly data would lead us to conclude that people in Delhi suffered less from poor health than they actually do.
Underreporting of illness is problematic in and of itself, but what makes the authors’ finding more striking is that the effect of reporting period is different for rich people than for poor people. In particular, there is less of a difference in rich people’s monthly vs. weekly reports that there is between poor people’s monthly vs. weekly reports. So, even though poor people are certainly “sicker” than rich people in the weekly data, this is not the case for all indicators of illness in the monthly data. So reporting periods will influence the way we think about the determinants of illness and health seeking behavior.
A particularly interesting finding is that in the weekly data, the poor in Delhi actually use health care providers more than rich. The authors use this striking point to argue that policy conversations that lament poor people’s lack of access to health care should instead focus on quality of care. While this is certainly true for residents of Delhi, a large Indian city, policy conversations about the health of people in remote rural areas will almost certainly need to be more complicated, and include access to care (which, one of the authors of this study has shown in previous work to be severely limited by the fact that doctors and nurses often don’t come to work) quality of care, and basic public health measures.