Fsdb::Filter::dbrvstatdiff(3pm)

1Fsdb::Filter::dbrvstatdUisfefr(3C)ontributed Perl DocumeFnstdabt:i:oFnilter::dbrvstatdiff(3)
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NAME

6       dbrvstatdiff - evaluate statistical differences between two random
7       variables
8

SYNOPSIS

10           dbrvstatdiff [-f format] [-c ConfRating]
11               [-h HypothesizedDifference] m1c sd1c n1c m2c sd2c n2c
12
13       OR
14
15           dbrvstatdiff [-f format] [-c ConfRating] m1c n1c m2c n2c
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DESCRIPTION

18       Produce statistics on the difference of sets of random variables.  If a
19       hypothesized difference is given (with "-h"), to does a Student's
20       t-test.
21
22       Random variables are specified by:
23
24       "m1c", "m2c"
25           The column names of means of random variables.
26
27       "sd1c", "sd2c"
28           The column names of standard deviations of random variables.
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30       "n1c", "n2c"
31           Counts of number of samples for each random variable
32
33       These values can be computed with dbcolstats.
34
35       Creates up to ten new columns:
36
37       "diff"
38           The difference of RV 2 - RV 1.
39
40       "diff_pct"
41           The percentage difference (RV2-RV1)/1
42
43       "diff_conf_{half,low,high}" and "diff_conf_pct_{half,low,high}"
44           The half half confidence intervals and low and high values for
45           absolute and relative confidence.
46
47       "t_test"
48           The T-test value for the given hypothesized difference.
49
50       "t_test_result"
51           Given the confidence rating, does the test pass?  Will be either
52           "rejected" or "not-rejected".
53
54       "t_test_break"
55           The hypothesized value that is break-even point for the T-test.
56
57       "t_test_break_pct"
58           Break-even point as a percent of m1c.
59
60       Confidence intervals are not printed if standard deviations are not
61       provided.  Confidence intervals assume normal distributions with common
62       variances.
63
64       T-tests are only computed if a hypothesized difference is provided.
65       Hypothesized differences should be proceeded by <=, >=, =.  T-tests
66       assume normal distributions with common variances.
67

OPTIONS

69       -c FRACTION or --confidence FRACTION
70           Specify FRACTION for the confidence interval.  Defaults to 0.95 for
71           a 95% confidence factor (alpha = 0.05).
72
73       -f FORMAT or --format FORMAT
74           Specify a printf(3)-style format for output statistics.  Defaults
75           to "%.5g".
76
77       -h DIFF or --hypothesis DIFF
78           Specify the hypothesized difference as "DIFF", where "DIFF" is
79           something like "<=0" or ">=0", etc.
80
81       This module also supports the standard fsdb options:
82
83       -d  Enable debugging output.
84
85       -i or --input InputSource
86           Read from InputSource, typically a file name, or "-" for standard
87           input, or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue
88           objects.
89
90       -o or --output OutputDestination
91           Write to OutputDestination, typically a file name, or "-" for
92           standard output, or (if in Perl) a IO::Handle, Fsdb::IO or
93           Fsdb::BoundedQueue objects.
94
95       --autorun or --noautorun
96           By default, programs process automatically, but Fsdb::Filter
97           objects in Perl do not run until you invoke the run() method.  The
98           "--(no)autorun" option controls that behavior within Perl.
99
100       --help
101           Show help.
102
103       --man
104           Show full manual.
105

SAMPLE USAGE

107   Input:
108           #fsdb title mean2 stddev2 n2 mean1 stddev1 n1
109           example6.12 0.17 0.0020 5 0.22 0.0010 4
110
111   Command:
112           cat data.fsdb | dbrvstatdiff mean2 stddev2 n2 mean1 stddev1 n1
113
114   Output:
115           #fsdb title mean2 stddev2 n2 mean1 stddev1 n1 diff diff_pct diff_conf_half diff_conf_low diff_conf_high diff_conf_pct_half diff_conf_pct_low diff_conf_pct_high
116           example6.12 0.17    0.0020  5       0.22    0.0010  4       0.05    29.412  0.0026138       0.047386        0.052614        1.5375  27.874  30.949
117           #  | dbrvstatdiff mean2 stddev2 n2 mean1 stddev1 n1
118
119   Input 2:
120       (example 7.10 from Scheaffer and McClave):
121
122           #fsdb title x2 sd2 n2 x1 sd1 n1
123           example7.10 9 35.22 24.44 9 31.56 20.03
124
125   Command 2:
126           dbrvstatdiff -h '<=0' x2 sd2 n2 x1 sd1 n1
127
128   Output 2:
129           #fsdb title n1 x1 sd1 n2 x2 sd2 diff diff_pct diff_conf_half diff_conf_low diff_conf_high diff_conf_pct_half diff_conf_pct_low diff_conf_pct_high t_test t_test_result
130           example7.10 9 35.22 24.44 9 31.56 20.03 3.66 0.11597 4.7125 -1.0525 8.3725 0.14932 -0.033348 0.26529 1.6465 not-rejected
131           #  | /global/us/edu/ucla/cs/ficus/users/johnh/BIN/DB/dbrvstatdiff -h <=0 x2 sd2 n2 x1 sd1 n1
132
133   Case 3:
134       A common use case is to have one file with a set of trials from two
135       experiments, and to use dbrvstatdiff to see if they are different.
136
137       Input 3:
138
139           #fsdb case trial value
140           a  1  1
141           a  2  1.1
142           a  3  0.9
143           a  4  1
144           a  5  1.1
145           b  1  2
146           b  2  2.1
147           b  3  1.9
148           b  4  2
149           b  5  1.9
150
151   Command 3:
152           cat two_trial.fsdb |
153               dbmultistats -k case value |
154               dbcolcopylast mean stddev n |
155               dbrow '_case eq "b"' |
156               dbrvstatdiff -h '=0' mean stddev n copylast_mean copylast_stddev copylast_n |
157               dblistize
158
159       Output 3:
160
161               #fsdb -R C case mean stddev pct_rsd conf_range conf_low conf_high conf_pct sum sum_squared min max n copylast_mean copylast_stddev copylast_n diff diff_pct diff_conf_half diff_conf_low diff_conf_high diff_conf_pct_half diff_conf_pct_low diff_conf_pct_high t_test t_test_result t_test_break t_test_break_pct
162               case: b
163               mean: 1.98
164               stddev: 0.083666
165               pct_rsd: 4.2256
166               conf_range: 0.10387
167               conf_low: 1.8761
168               conf_high: 2.0839
169               conf_pct: 0.95
170               sum: 9.9
171               sum_squared: 19.63
172               min: 1.9
173               max: 2.1
174               n: 5
175               copylast_mean: 1.02
176               copylast_stddev: 0.083666
177               copylast_n: 5
178               diff: -0.96
179               diff_pct: -48.485
180               diff_conf_half: 0.12202
181               diff_conf_low: -1.082
182               diff_conf_high: -0.83798
183               diff_conf_pct_half: 6.1627
184               diff_conf_pct_low: -54.648
185               diff_conf_pct_high: -42.322
186               t_test: -18.142
187               t_test_result: rejected
188               t_test_break: -1.082
189               t_test_break_pct: -54.648
190
191               #  | dbmultistats -k case value
192               #   | dbcolcopylast mean stddev n
193               #   | dbrow _case eq "b"
194               #   | dbrvstatdiff -h =0 mean stddev n copylast_mean copylast_stddev copylast_n
195               #   | dbfilealter -R C
196
197       (So one cannot say that they are statistically equal.)
198

CLASS FUNCTIONS

203   new
204           $filter = new Fsdb::Filter::dbrvstatdiff(@arguments);
205
206       Create a new dbrvstatdiff object, taking command-line arguments.
207
208   set_defaults
209           $filter->set_defaults();
210
211       Internal: set up defaults.
212
213   parse_options
214           $filter->parse_options(@ARGV);
215
216       Internal: parse command-line arguments.
217
218   setup
219           $filter->setup();
220
221       Internal: setup, parse headers.
222
223   run
224           $filter->run();
225
226       Internal: run over each rows.
227

AUTHOR and COPYRIGHT

229       Copyright (C) 1991-2018 by John Heidemann <johnh@isi.edu>
230
231       This program is distributed under terms of the GNU general public
232       license, version 2.  See the file COPYING with the distribution for
233       details.
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237perl v5.32.0                      2020-11-16     Fsdb::Filter::dbrvstatdiff(3)