freebsd-dev/usr.bin/ministat/ministat.1

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.Dd November 10, 2012
.Dt MINISTAT 1
.Os
.Sh NAME
.Nm ministat
.Nd statistics utility
.Sh SYNOPSIS
.Nm
.Op Fl Ans
.Op Fl C Ar column
.Op Fl c Ar confidence_level
.Op Fl d Ar delimiter
.Op Fl w Op width
.Op Ar
.Sh DESCRIPTION
The
.Nm
command calculates fundamental statistical properties of numeric data
in the specified files or, if no file is specified, standard input.
.Pp
The options are as follows:
.Bl -tag -width Fl
.It Fl A
Just report the statistics of the input and relative comparisons,
suppress the ASCII-art plot.
.It Fl n
Just report the raw statistics of the input, suppress the ASCII-art plot
and the relative comparisons.
.It Fl s
Print the average/median/stddev bars on separate lines in the ASCII-art
plot, to avoid overlap.
.It Fl C Ar column
Specify which column of data to use.
By default the first column in the input file(s) are used.
.It Fl c Ar confidence_level
Specify desired confidence level for Student's T analysis.
Possible values are 80, 90, 95, 98, 99 and 99.5 %
.It Fl d Ar delimiter
Specifies the column delimiter characters, default is SPACE and TAB.
See
.Xr strtok 3
for details.
.It Fl w Ar width
Width of ASCII-art plot in characters.
The default is the terminal width, or 74 if standard output is not a
terminal.
.El
.Pp
A sample output could look like this:
.Bd -literal -offset indent
  $ 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
.Ed
.Pp
If
.Nm
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.
.Pp
You have the option of lowering your standards by specifying a
lower confidence level:
.Bd -literal -offset indent
  $ 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)
.Ed
.Pp
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.
.Sh SEE ALSO
Any mathematics text on basic statistics, for instances Larry Gonicks
excellent "Cartoon Guide to Statistics" which supplied the above example.
.Sh HISTORY
The
.Nm
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.
.Pp
From
.Fx 5.2
it has lived in the source tree as a developer tool, graduating
to the installed system from
.Fx 8.0 .