Abstract
The aim of this study was to estimate sample size for the physical and physico- chemical characteristics of the peduncles and nuts of the cashew (Anacardium occidentale L.) as an aid in research using classical analytical methods and near-infrared (NIR) spectroscopy. Sample sizes were estimated by means of uniform stratified sampling, comprising six strata (S1, S2, ..., S6) corresponding to the clones A+C 276/1, BRS 226, CCP 76, HI58-92-2, PRO 553/2 and PRO 555/2. Determining the size of the sample for each stratum depends on the variance of the characteristic under evaluation and the accepted margin of error B of the estimates, or on the desired precision in the results. The greater the variance of the stratum, the greater the size of the sample, the smaller the acceptable margin of error of the estimates, and the greater the desired precision of the results. For an error B = 0.2 g, the sample size for nuts of the A+C276/1 clone (stratum S1), with variance s2 = 5.1568, was n1 = 30 nuts. For firmness, with B = 0.50 N, the sample size for the PRO 555/2 clone (S6) was n6 = 22 peduncles. For vitamin C, which presented the highest variances, the sample size of the BRS 226 clone (S2), with B = 10 mg100-1g, was n2 = 38 peduncles. The variables pH, soluble solids, titratable acidity and soluble sugars presented the smallest variances, giving the smallest sample sizes for each of the clones.
Index terms
sample sizing; uniform stratified random sampling; sampling accuracy; near-infrared spectroscopy