The Ghana Statistical Service (GSS) is calling for a nationwide overhaul of how food sold in traditional markets is measured and recorded, saying standardized conversion factors for non-standard units such as cups, tins and sacks are needed to improve the accuracy of inflation, agricultural production and national accounts data.
The recommendations follow the publication of national reports examining how non-standard units (NSUs) are used by households, farmers and traders across Ghana. The studies found that identical measures often represent significantly different quantities depending on the region, creating inconsistencies in official statistics and complicating policy decisions.
At the center of the recommendations is the integration of nationally validated conversion factors into the Consumer Price Index (CPI), agricultural statistics, household consumption surveys and Gross Domestic Product (GDP) estimation.
The GSS said incorporating standardized conversion factors into the compilation of the CPI would improve the precision of inflation measurement by ensuring that food prices collected in local markets are converted into consistent weights and volumes. The agency also recommended applying the conversion system across agricultural production statistics, household expenditure surveys and the national accounts framework to strengthen the reliability and comparability of official economic data.
To support the reforms, the statistical service is proposing the establishment of a national database of non-standard unit conversion factors that would serve as a permanent reference for government institutions, researchers and development partners. The database would be accompanied by a photographic library documenting commonly used containers and measures, while the conversion factors would be reviewed and updated periodically to reflect changes in market practices, container sizes and inflation.
It also called for greater harmonization of measurement practices across markets and farmgate transactions to reduce regional inconsistencies that currently affect the quality of agricultural statistics.
The recommendations are supported by findings showing substantial variations in the quantity represented by commonly used market measures across the country.
The Household Report found that a small cup of locally produced rice weighs an average of 0.352 kilograms nationally but ranges from 0.320 kilograms in the Savannah Region to 0.378 kilograms in the Greater Accra Region. Similar regional differences were recorded for gari and yams, indicating that households often use identical measures to represent different quantities.
At the farmgate level, the Farmgate Report found even wider disparities. A cocoa, or jute, sack used to trade dried yellow maize weighs as little as 131.1 kilograms in the Greater Accra Region and as much as 198 kilograms in the Bono East Region, a difference of nearly 67 kilograms despite being described by the same unit of measure.
The Market Report also identified significant regional differences. A medium-sized margarine tin used to measure food weighs an average of 0.276 kilograms nationally but ranges from 0.228 kilograms in the Ahafo Region to 0.346 kilograms in the Ashanti Region. Likewise, medium-sized yams varied considerably in weight across regions, highlighting the limitations of size-based classifications for statistical purposes.
The GSS said the three publications collectively provide Ghana’s first nationally representative conversion factors for non-standard units, enabling widely used local measurements to be translated into standardized kilograms and litres.
According to the GSS, adopting the recommendations would improve the quality, consistency and comparability of official statistics while providing policymakers, researchers and development partners with more reliable evidence for economic planning, agricultural policy and market analysis.
