A SEQUENTIAL SAMPLING TECHNIQUE FOR SPRUCE BUDWORM EGG SURVEYS

Abstract

The object in extensive spruce budworm egg surveys is to classify the infestation as light, moderate, or severe, at a large number of sampling points. The sequential plan, having no fixed sample size, was tested in 1953. It proved very useful, particularly in eliminating superfluous sampling at points where the infestation was definitely light or definitely severe. Curves showing operating characteristics and average sample numbers in relation to population mean permitted an appraisal of the plan in advance of the field test. Field parties were provided with simple tabulations prepared from the acceptance and rejection lines. With an expenditure of 1300 man-days, more than 1000 points were classified in northern New Brunswick.