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Mathematical Error in Rubber Statistics

Grievance No.DOCOM/E/2019/00176 dated 10.02.2019  on PG Portal

A Reply received from Secretary

The globally accepted formula for estimating and verifying NR production, consumption, trade and stock is as follows.
Opening Stock + Production + lmport = Consumption + Export + Closing Stock
Hence, the following formula can be used to estimate Closing Stock.
Closing Stock = (Opening Stock + Production + lmport) - (Consumption + Export)
Closing Stock can also be alternatively estimated based on survey approach by collecting and collating data on stock with small growers, estates, processors, dealers and product manufacturers. Rubber Board has been using survey method for arriving at NR stock estimates as reliability is higher for such estimates. 

Closing stock estimated through formulae method and survey method showed wide variations during the period from 2009-10 to 2013-14. This mismatch could be due to overestimation of NR production or underestimation of consumption or a combination of both. Consumption, import and export of NR are objective estimates as they are primarily based on returns and documents. NR production is a subjective estimate as it is mainly based on monthly sample survey and any error in production is reflected in stock of rubber as well. Hence, NR production statistics during 2009-10 to 2013-14 were reviewed by an Expert panel and recommended for revision based on a statistical regression model.

With regard to stock of NR, the Expert Panel recommended that it should include rubber with growers, dealers, processors and manufacturers based on surveys and returns collected and that the standard equality between (opening stock + production + import) and (consumption + export + closing stock) should be maintained as far as possible. 

In commodity modelling, a certain percentage of allowable error will always exist due to the estimation procedure. Production, consumption and stock are estimates and' there can be some extent of permissible error. This error was pointed out by you as mismatch. 

It may be noted that the error in estimates has been considerably reduced after revision of statistical methodology in 2015-16 based on the recommendations of the Expert Panel. For the year 2016-17 and 2017-18, error levels are only 1.2o/o and 1.7% respectively of the total NR consumption in the country which is less than the permissible error of up Io 5%. 

A Statistics Consultative Panel (SCP) was constituted in April 2016 comprising representatives of rubber producing, processing, trading and consuming sectori for facilitating regular consultations and discuslions with different segments of rubber sector on statistics related matters. The statistics published byihe Board and.methodology are regularly discussed in SCP and the last meeting was held on 4tn January 2019. The unavoidable error in statistics on stock has no link with volume of rubber


A reply send to
Deputy Director Excise <>,

Please follow the link (mathematical error in Indian Rubber Statistics in detail) to see the -Ve mathematical error from 2004-05 to 2009-10 for a price hike in 2010-11 and 2011-12. The revised statistics during 2010-11 to 2013-14 by an expert pannel was to correct the mistake of esimated shortage provided to Sri Joy Abraham Mp in Rajyasabha. The Expert panel reduced the production from 844000 tonnes to 774000 Tonnes for the year 2013-14. I wonder how the Opening Stock + Production + Import and Consumption + Export + Closing Stock can't tally with out a missing figure.
Few links are available as more evidence. (including Answer to Question NO : 1887 - Shri Joy Abraham in Rajyasabha ) (in details with hyperlinks to fetch the data)



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Please note that this is the opinion of the author and is Not Certified by ICAR or any of its authorised agents.