has part is about has_specified_input has_specified_output achieves_planned_objective is denoted by has value scalar measurement datum data set population statistical test hypothesis statistical hypothesis test objective Student's t-test 1 2 true 1 true 1 1 2 1 WEB: http://en.wikipedia.org/wiki/T-test Student's t-test James Malone t-test Studen't t-test is a data transformation with the objective of a statistical hypothesis test in which the test statistic has a Student's t distribution if the null hypothesis is true. It is applied when the population is assumed to be normally distributed but the sample sizes are small enough that the statistic on which inference is based is not normally distributed because it relies on an uncertain estimate of standard deviation rather than on a precisely known value. Alejandra Gonzalez-Beltran Philippe Rocca-Serra t.test(dependent variable ~ independant variable, data = dataset, var.equal = FALSE) http://stat.ethz.ch/R-manual/R-patched/library/stats/html/t.test.html study design independent variable study design dependent variable normal distribution hypothesis false positive rate Student's t distribution dichotomous variable t-statistic study group population continuous variable p-value ready for release metadata incomplete obi.owl