US EPA: Sample Size and Sampling Frequency Estimator
How many samples should be collected during an environmental study? The answer is often based upon the best professional judgment of an investigator and subjective answers will vary, depending on who you ask. The best answer will be based on an objective approach, dependent on a number of factors, including the desired statistical power and level of confidence in the final decision and the variability of the environmental attribute of interest.
Sample Size & Sampling Frequency Estimator is a 32-bit Windows application that assists in estimation of sample sizes required to support commonly applied water monitoring objectives. The program eliminates the need to read values from tables of statistical distributions and perform iterative calculations to arrive at an estimate. The online help provides a quick reference for formulae, from peer reviewed literature, required to estimate sample sizes. It does not provide comprehensive coverage of study designs or statistical analyses, nor is it a substitute for a consultation with an applied statistician during the design of a study.
This US EPA link provides system requirements, documentation, and the link to download the current version (beta).
Water Quality/Quantity, Technology(not GIS or GPS)