A question we frequently encounter – for reasons of access, cost and reliability of data.
Interesting findings therefore, in this paper studying micro-enterprises in the township of Soweto, South Africa:
We randomly assign micro-enterprises to three groups, who receive are interviewed face-to-face at monthly intervals (mimicking a standard method of collecting data from micro-enterprises), face-to-face at weekly intervals, and by mobile phone at weekly intervals. We find high frequency data collection is useful: it captures extensive volatility in a number of measures not visible in less frequent data collection. We also find is viable: on most measures and at most quantiles of the distribution, data patterns are indistinguishable in interviews conducted weekly or monthly and face-to-face or by phone.
High frequency surveys (which are easier when conducted over the phone) provide valuable data; and the authors do not find any significant difference in attrition rates between phone and face-to-face surveys. Also, variable costs are about 40% lower for phone surveys – the cost savings would likely be higher if conducted over widely dispersed rural areas instead of an urban township.