MINISTAT(1) | FreeBSD General Commands Manual | MINISTAT(1) |
NAME
ministat — statistics utilitySYNOPSIS
ministat | [ -Ans][ -C column][ -c confidence_level][ -d delimiter][ -w [ width]][ file ...] |
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, default is 74.
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.
November 10, 2012 | FreeBSD |