NAME

ministat — statistics utility

SYNOPSIS

DESCRIPTION

The ministat command calculates fundamental statistical properties of numeric data in the specified files or, if no file is specified, standard input.

The options are as follows:

-A

Just report the statistics of the input and relative comparisons, suppress the ASCII-art plot.

-n

Just report the raw statistics of the input, suppress the ASCII-art plot and the relative comparisons.

-s

Print the average/median/stddev bars on separate lines in the ASCII-art plot, to avoid overlap.

-C column

Specify which column of data to use. By default the first column in the input file(s) are used.

-c confidence_level

Specify desired confidence level for Student's T analysis. Possible values are 80, 90, 95, 98, 99 and 99.5 %

-d delimiter

Specifies the column delimiter characters, default is SPACE and TAB. See strtok(3) for details.

-w width

Width of ASCII-art plot in characters. The default is the terminal width, or 74 if standard output is not a terminal.

A sample output could look like this:

  $ ministat -s -w 60 iguana chameleon
  x iguana
  + chameleon
  +------------------------------------------------------------+
  |x      *  x            *      +              + x           +|
  | |________M______A_______________|                          |
  |             |________________M__A___________________|      |
  +------------------------------------------------------------+
      N        Min        Max     Median        Avg       Stddev
  x   7         50        750        200        300    238.04761
  +   5        150        930        500        540    299.08193
  No difference proven at 95.0% confidence

If ministat tells you, as in the example above, that there is no difference proven at 95% confidence, the two data sets you gave it are for all statistical purposes identical.

You have the option of lowering your standards by specifying a lower confidence level:

  $ ministat -s -w 60 -c 80 iguana chameleon
  x iguana
  + chameleon
  +------------------------------------------------------------+
  |x      *  x            *      +              + x           +|
  | |________M______A_______________|                          |
  |             |________________M__A___________________|      |
  +------------------------------------------------------------+
      N        Min        Max     Median        Avg       Stddev
  x   7         50        750        200        300    238.04761
  +   5        150        930        500        540    299.08193
  Difference at 80.0% confidence
        240 +/- 212.215
        80% +/- 70.7384%
        (Student's t, pooled s = 264.159)

But a lower standard does not make your data any better, and the example is only included here to show the format of the output when a statistical difference is proven according to Student's T method.

SEE ALSO

Any mathematics text on basic statistics, for instances Larry Gonicks excellent "Cartoon Guide to Statistics" which supplied the above example.

HISTORY

The ministat command was written by Poul-Henning Kamp out of frustration over all the bogus benchmark claims made by people with no understanding of the importance of uncertainty and statistics.

From FreeBSD 5.2 it has lived in the source tree as a developer tool, graduating to the installed system from FreeBSD 8.0.