Rapid Assessment Method or RAM is a multi-purpose, fast, low resource small area survey method producing spatially representative information on a range of demographic, behavioural and public health indicators.

RAM uses various robust sampling and statistical techniques that although common in the social sciences and in high level clinical drug trials are not standard practice in public health. These techniques increase efficiency with which the survey uses the data that is collected allowing smaller sample sizes to produce the same levels of precision. For example a standard 30 by 30 cluster survey usually requires a sample size of 900 (minimum 600), whereas a RAM survey can produce the same level of statistical precision from a sample of only 200, thereby saving time and cost.

These techniques include probit analysis otherwise known as the “area under distribution curves” technique. Probit uses basic statistical measures such as the median and inter-quartile range (IQR) to estimate a proportion compared to a simple analysis of binary or dichotomous variables. Probit analysis is a proven technique in a wide range of statistical applications in public health.

RAM analysis also uses a system called bootstrapping (also known more technically as computer-intensive re-sampling statistical methods). In simple terms, this approach basically harnesses computing power to fully maximise the survey sample in order to provide as much, if not more precision, precise of survey results compared to conventional higher sample size type of surveys such as. Valid International’s innovation is the development and adoption of a blocking weighted bootstrap to cross-sectional surveys of arbitrary complex design with unequal selection probabilities.

By lowering resource requirement RAM has a role in a range of monitoring and impact evaluations that require a series of measurements over time conducted through multiple surveys.


Myatt, M and Valid International. A proposal for a rapid assessment method.

Myatt, M and Valid International. Update No. 1: Development of a rapid assessment method.

Myatt, M and Valid International. Update No. 2: Development of a rapid assessment method.

Guevarra, E, 2014. Livelihoods, nutrition and public health assessment in six districts of Bakool, Bay and Middle Shabelle regions of South Somalia. Valid International, Oxford.