12345678910111213141516171819202122232425262728293031323334353637383940414243 |
- /* statistics/ttest_source.c
- *
- * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2007 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 3 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;
- }
|