Statistics Toolbox

tcdf

Student's t cumulative distribution function (cdf)

Syntax

• P = tcdf(X,V)
  

Description

P = tcdf(X,V) computes Student's t cdf at each of the values in X using the corresponding degrees of freedom in V. Vector or matrix inputs for X and V must be the same size. A scalar input is expanded to a constant matrix with the same dimensions as the other inputs. The parameters in V must be positive integers.

The t cdf is

The result, p, is the probability that a single observation from the t distribution with degrees of freedom will fall in the interval (- x].

Examples

Suppose 10 samples of Guinness beer have a mean alcohol content of 5.5% by volume and the standard deviation of these samples is 0.5%. What is the probability that the true alcohol content of Guinness beer is less than 5%?

• t = (5.0 - 5.5) / 0.5;
  probability = tcdf(t,10 - 1)
  probability =
      0.1717
  

See Also

cdf, tinv, tpdf, trnd, tstat

tblwrite

tdfread