Table 4.

Quantitative metrics of stove adoption using Stove Use Monitors (SUMs). Ten of the main metrics formulated in this paper are tabulated (central cells) by increasing level of detail (first column: days in use, meals, hours in use), duration of the monitoring period (second column: one day, T number of days) and size of the monitored sample (third and fourth columns: one stove, group of stoves). The main applications of the metrics are summarized in the right and lower margins of the table. The factors on the right margin carry over from the top down, i.e. given an appropriate sample size and monitoring period the metrics for time in use (lower rows) could also reflect information about factors acting at the level of meals and days in use (upper rows). The corresponding absolute metrics: the number of stove-days in use, the number of meals and the number of hours can also be used to quantify the cumulative stove activity in a day or a period.

Level of Detail	Monitoring Period	Size of the monitored sample
		One stove	Group of I stoves
DAYS IN USE	One day		% stoves used Display patterns of use (Fig. 3).	Factors affecting whether the stove is used at all in a day: migration, fuel availability, weather, local festivals, stove break down, stove abandonment.
	T days	% days in use in T Correlate with meals to analyze the stacking of fuels/stoves (Fig. 6).	% stove-days in use in T Comparisons with usage indicators for the same T (Fig. 4).
MEALSa	One day		Average meals per day Display patterns of use (Fig. 3).	Factors affecting the frequency of use within days: special meal celebrations and other household needs and preferences to combine the use of multiple fuel/stoves.
	T days	Average daily meals Correlate with % days in use to analyze the stacking of stoves/fuels (Fig. 6)	Average meals in T Comparisons with usage indicators for the same T (Fig. 4).
TIME IN USEb (HOURS)	One day	% day in use Correlate with meals to understand cooking dynamics.	% hours per day in group Display patterns of use.	Factors affecting the duration of stove use on a day: household routines, type of cooking tasks performed, amount and type of fuel consumed, stove type, stove operation and maintenance practices and environmental conditions.
	T days	% daily hours in T Correlate with days in use and meals to analyze the stacking of stoves/fuels.	% hours in group Comparisons with usage indicators for the same T.
		Individual temporal patterns: seasons and increasing/decreasing trends of sustained use.	Longitudinal group patterns: acceptance, initial adoption, sustained use trends and seasons.

^aThe definition of “meals” requires special attention to ensure consistency between the interpretation of SUMs signals and the particular stove type, cooking practices and cultural context of the monitored population (e.g. to ensure that the stirring of fuel is not counted as multiple meals and that short tasks like tea preparation and longer tasks such as tortilla making are weighed as desired). In this paper we used information about the number and length of meals from recall questionnaires [ref] to ensure the consistency of our meal definition.

^bThe use of differential-temperature signals [ref] is required in most cases to accurately estimate time in use (e.g. to avoid counting the cooling-down of the stove as time in use and to correct for the influence of ambient temperature or external heating sources).