Insufficient and Unreliable Data The economic value of a development plan depends to a great extent on the quality and reliability of the statistical data on which it is based. When these data are weak, unreliable, or nonexistent, as in many poor countries, the accuracy and internal consistency of economy wide quantitative plans are greatly diminished. And when unreliable data are compounded by an inadequate supply of qualified economists, statisicians, and other planning personnel (as is also the situation in most poor nations), the attempt to formulate and carry out a comprehensive and detailed
development plan is likely to be frustrated at all levels.