CascadiaPHP 2024

# stats_cdf_t

(PECL stats >= 1.0.0)

stats_cdf_tCalculates any one parameter of the t-distribution given values for the others

### Description

stats_cdf_t(float \$par1, float \$par2, int \$which): float

Returns the cumulative distribution function, its inverse, or one of its parameters, of the t-distribution. The kind of the return value and parameters (par1 and par2) are determined by which.

The following table lists the return value and parameters by which. CDF, x, and nu denotes cumulative distribution function, the value of the random variable, and the degrees of freedom of the t-distribution, respectively.

Return value and parameters
which Return value par1 par2
1 CDF x nu
2 x CDF nu
3 nu x CDF

### Parameters

par1

The first parameter

par2

The second parameter

which

The flag to determine what to be calculated

### Return Values

Returns CDF, x, or nu, determined by which.

add a note

### User Contributed Notes 2 notes

Brian
13 years ago
In order to match the output of this function with Excel's TDIST function, you must take 1 - the value. For example, for a two-tailed T-distribution for x=4 and degrees of freedom=2, the formula would be:

(1 - stats_cdf_t(4, 2, 1)) * 2

For a single tail, do not include the multiply by 2 portion.
-4
Anonymous
12 years ago
Input and return values of stats_cdf_t depends on the \$which-parameter:
<?php
function get_t_p(\$t, \$df){
return
stats_cdf_t(\$t, \$df, 1);
}
function
get_t_t(\$p, \$df){
return
stats_cdf_t(\$p, \$df, 2);
}
function
get_t_df(\$p, \$t){
return
stats_cdf_t(\$p, \$t, 3);
}
?>