Sighting example of 1988-89 when the actual rainfall exceeded the normal rainfall by a maximum margin of 17.4 per cent, the report says that the national income went up by the highest ever margin of 10.2 per cent. The year 1975-76 happened to be yet another year of prosperity when national income went up by 9.2 per cent. This jump also could be attributed to one of the best monsoons and actual rainfall exceeded the normal rainfall by the second highest margin of 16.7 per cent during that year.

During 1972-73 and 1979-80 when the actual quantum of rainfall fell short of the normal level by 22 per cent and 16 per cent respectively,the growth in national income was negative. Despite advancement in the compilation of statistics, India does not yet have a comprehensive weather index on the lines of the Stallings Weather Index developed in the USA to take note of the impact of weather distortions on the national economy.

However, the rainfall index developed in this study, despite its limitations as a proxy for the weather, proves that the weather plays a crucial and commanding role in determining fluctuations in national income.

Measured by the value of final consumption expenditure, food accounts for a share of 35.4 percent in gross national income. Secondly, higher farm income and its multiplier affect on the other sectors raise savings and thus investment above the average levels. Given the vagaries of the monsoon and a high share of the farm sector in the national economy, it is always advisable to wait at least until the end of September even to make a preliminary estimate about the likely growth national income during any givenyear.

For the same reason, the recent forecast by NCAER of the national income rising by around 5.56 per cent during the current year should be taken with a pinch of salt, says MP Wagle, director of Mangesh International Services.