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tval(x [,df:T]), x a REAL vector or matrix

Keywords: probabilities, descriptive statistics, comparisons
tval(x) computes the Student's t-statistic for testing the null
hypothesis that the data in REAL vector x have mean zero.  When x is a
matrix, the results is a vector with the t-statistics for each column of

tval(x,df:T) produces a structure with two components, 't' containing
the t-statistic and 'df' containing the degrees of freedom.  When x is a
matrix, each component is a vector of length ncols(x).

When x contains MISSING values, an informative message is printed.

When the null hypothesis mean is something other than zero, say delta,
tval(x-delta) will produce the correct t value for that null hypothesis.
For example, to test H0: E[x] = 3, use tval(x-3).

P values may be computed using the function cumstu() or the macro
twotailt(), for example, by
  Cmd> @result <- tval(x,df:T);twotailt(@result$t,@result$df)

See also topics t2val(), tint(), t2int(), cumstu(), and twotailt().

Gary Oehlert 2003-01-15