In order to determine if two sets of data are significantly from each other, standard deviations are compared via f-test, and means are compared via t-test. the following data gave the recovery of bromide from spiked samples of vegetable matter, measured by using a gas-liquid chromatographic method. the same amount of potassium bromide was added to each specimen. does the sample matrix interfere in the precision of the method? does the sample matrix interfere in the recoveries? the following percentage recoveries were obtained in a comparison between a new method and the official method of determining oxyphenbutazone. does the mean result obtained by the two methods differ significantly?