Corrigendum

The articles presents results concerningthe significances of the sample lead and illustrates their uses. They apply to the sample lead of one party over another in political polls, one productover another in market research surveys, share of the market of one company over another in industrial studies, one class over another in social investigations, one programme over another in TV viewing surveys, etc. They enable calculation of confidence intervals and required sample sizes, testing of hypotheses, etc. They deal with sampling from finite and infinite populations, with and without replacement, sampling from population with overlapping classifications, stratified sampling, optimum allocation to strata, etc. Derivation of the results is given in the appendices. Some of the proofs are rather complicated, but the final results are quite simple and easy to use.