| /* statistics/ttest_source.c |
| * |
| * Copyright (C) 1996, 1997, 1998, 1999, 2000 Jim Davies, Brian Gough |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or (at |
| * your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, but |
| * WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
| */ |
| |
| double |
| FUNCTION(gsl_stats,ttest) (const BASE data1[], |
| const size_t stride1, const size_t n1, |
| const BASE data2[], |
| const size_t stride2, const size_t n2) |
| { |
| /* runs a t-test between two datasets representing independent |
| samples. Tests to see if the difference between means of the |
| samples is different from zero */ |
| |
| /* find means for the two samples */ |
| const double mean1 = FUNCTION(gsl_stats,mean) (data1, stride1, n1); |
| const double mean2 = FUNCTION(gsl_stats,mean) (data2, stride2, n2); |
| |
| /* find pooled variance for the two samples */ |
| const double pv = FUNCTION(gsl_stats,pvariance) (data1, stride1, n1, data2, stride2, n2); |
| |
| /* calculate the t statistic */ |
| const double t = (mean1 - mean2) / (sqrt (pv * ((1.0 / n1) + (1.0 / n2)))); |
| |
| return t; |
| } |
| |
