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Bureau of Labor Statistics > Import/Export Price Indexes > Home

Approximating missing data points

Observations in the Import/Export Price Indexes (MXPI) series can be missing when a data value of a regularly published price index series is suppressed due to an inability to collect the prices related to the series for various reasons, such as a lapse in appropriations or the failure of respondents to provide prices. More details are provided in the Handbook of Methods, Publication Guidelines.

Missing data points can be approximated by taking the geometric mean of the adjacent index values. The calculation steps are to take the product of the index value for the months immediately before and after the month with the missing index value and then take the square root of that product. The resulting value is the estimated missing index value.

An example is provided in table 1 for the missing export price index value in January 2019 of the BEA End Use Soybeans and soybean by-products series (EIUIQ00100).

Table 1, Soybeans and soybean by-products
Quantity	Representation	Value
Index value, December 2018		173.8
Index value, February 2019		176.6
Product of index values	173.8 * 176.6=	30,693.080
Square root of the product	√30,693.080=	175.194
Index value estimate, January 2019		175.2

Note: Data values calculated in this way cannot be interpreted as official MXPI series, as the calculation is based on two data points and not on the MXPI aggregation method. Percent changes based on approximated data should also be considered as unofficial estimates.

Last modified date: January 7, 2026