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student.h File Reference

t-test and F-test for comparing two means. More...

#include <stdlib.h>
#include <stdio.h>
#include <math.h>

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Functions

double t_two (double t, int Df)
 t_two(t, Df): returns the two-sided probability that t is equal to 0 with Df degrees of freedom. More...

double t_samevar (double Ave1, double Ave2, double Var1, double Var2, int n1, int n2, double *T)
 t_samevar(Ave1, Ave2, Var1, Var2, n1, n2, T): Student's t-test for two distributions that have the same "true" variance. More...

double t_diffvar (double Ave1, double Ave2, double Var1, double Var2, int n1, int n2, double *T)
 t_diffvar(Ave1, Ave2, Var1, Var2, n1, n2, T): Student's t-test for two distributions with different variances. More...

double f_test (double Var1, double Var2, int n1, int n2, double *Fval)
 f_test(Var1, Var2, n1, n2, Fval): Fisher's F-test to decide whether Var1, 2 are different variances. More...


Detailed Description

t-test and F-test for comparing two means.

Author(s):
Andras Aszodi
Date:
22-Nov-2001.

Definition in file student.h.


Function Documentation

double t_two ( double t,
int Df )
 

t_two(t, Df): returns the two-sided probability that t is equal to 0 with Df degrees of freedom.

Returns -1.0 on error.

double t_samevar ( double Ave1,
double Ave2,
double Var1,
double Var2,
int n1,
int n2,
double * T )
 

t_samevar(Ave1, Ave2, Var1, Var2, n1, n2, T): Student's t-test for two distributions that have the same "true" variance.

Ave1, 2 are the averages, Var1, 2 are the variances. (These should pass an F-test for the Var1==Var2 hypothesis.) n1, n2 are the number of data points. Return values: returns the probability (significance) level and also returns the t-stat value in *T if T!=NULL. Returns -1.0 if something was fishy plus prints a warning on stderr.

double t_diffvar ( double Ave1,
double Ave2,
double Var1,
double Var2,
int n1,
int n2,
double * T )
 

t_diffvar(Ave1, Ave2, Var1, Var2, n1, n2, T): Student's t-test for two distributions with different variances.

Ave1, 2 are the averages, Var1, 2 are the variances. (These should pass an F-test for the Var1!=Var2 hypothesis.) n1, n2 are the number of data points. Return values: returns the probability (significance) level and also returns the t-stat value in *T if T!=NULL. Returns -1.0 if something was fishy plus prints a warning on stderr.

double f_test ( double Var1,
double Var2,
int n1,
int n2,
double * Fval )
 

f_test(Var1, Var2, n1, n2, Fval): Fisher's F-test to decide whether Var1, 2 are different variances.

n1, n2 are the no. of data points. Return values: returns the F-statistics probability (significance) level. Also returns the F-value in *Fval if Fval!=NULL. Returns -1.0 if something silly happens.


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