Table of Contents

tzero - calculate Student’s t statistic versus zero mean (ERP statistics)
tzero [-o]opt [-h "Ascii header"]opt
*tzero* is used to
calculate Student’s t statistic on a set of data for the null hypothesis
that the population mean is 0. The data are taken from the standard input
as ASCII numbers until an end of file is encountered, at which time the
mean, standard deviation, standard error, number of data elements, t value
(with degrees of freedom), and probability of that t arising under the
null hypothesis are printed on the standard output. The input data can be
arranged in relatively free form with one or more numbers per line and
any number of lines. An end of file terminates the input. Usually the input
data are redirected from a file, but can be typed in interactively if desired.
Normally *tzero* calculates the probability as a two-tailed test; the *-o* option
causes *tzero* to calculate the probability as a one-tailed test (one half
the two-tailed value).

The *-h* option enables the user to prepend an ASCII
description to the output of *tzero* by immediately following the -h with
a string surrounded by double quotes (as shown in the synopsis above),
facilitating bookkeeping of multiple tests.

Jonathan C. Hansen
UCSD ERPL
*tzero* complains if there is only one data point,
as a test is impossible in this case.
The probability value is printed
only to four decimal places; hence p values of .0000 can be emitted and
should be interpreted as less than .0001.

**Table of Contents**