Streamflow was collected at various streamgages in western Pennsylvania in support of the scientific investigations report "Estimation of Base Flow on Ungaged, Periodically Measured Streams in Small Watersheds in Western Pennsylvania". Data were selected for the development of eleven regressions on three streamgage pairs to examine differences in the regression diagnostics and prediction interval based upon the data chosen for the regression. This dataset includes 1) data used to develop prediction intervals for the titled estimation site based upon the titled index streamgage, 2) zero streamflow information, and 3) evaluation of the prediction interval with non-runoff influenced data. For prediction interval development a Move.1 regression was developed between the titled estimation site and titled index streamgage. From this regression model, Pearson's correlation coefficient (r) is reported and the 95% prediction interval developed for the nonparametric method. The data set used for regression development contains zero streamflow data observed at the estimation site. From this data, the highest streamflow at the index streamgage where zero flow occurred at the estimation site (HISAZ) is recorded. For each evaluation, the same dataset is chosen, and it is not influenced by runoff. Determination of whether data falls within the prediction interval and the computation of the Nash-Sutcliffe Efficiency value is accomplished for this evaluation dataset. Streamflow that occurred the day of precipitation and two days after is considered influenced by runoff.