1DBRVSTATDIFF(1) User Contributed Perl Documentation DBRVSTATDIFF(1)
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6 dbrvstatdiff - evaluate statistical differences between two random
7 variables
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10 dbrvstatdiff [-f format] [-c ConfRating]
11 [-h HypothesizedDifference] m1c sd1c n1c m2c sd2c n2c
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13 OR
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15 dbrvstatdiff [-f format] [-c ConfRating] m1c n1c m2c n2c
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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.
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22 Random variables are specified by:
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24 "m1c", "m2c"
25 The column names of means of random variables.
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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
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33 These values can be computed with dbcolstats.
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35 Creates up to ten new columns:
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37 "diff"
38 The difference of RV 2 - RV 1.
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40 "diff_pct"
41 The percentage difference (RV2-RV1)/1
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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.
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47 "t_test"
48 The T-test value for the given hypothesized difference.
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50 "t_test_result"
51 Given the confidence rating, does the test pass? Will be either
52 "rejected" or "not-rejected".
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54 "t_test_break"
55 The hypothesized value that is break-even point for the T-test.
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57 "t_test_break_pct"
58 Break-even point as a percent of m1c.
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60 Confidence intervals are not printed if standard deviations are not
61 provided. Confidence intervals assume normal distributions with common
62 variances.
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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.
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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).
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73 -f FORMAT or --format FORMAT
74 Specify a printf(3)-style format for output statistics. Defaults
75 to "%.5g".
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77 -h DIFF or --hypothesis DIFF
78 Specify the hypothesized difference as "DIFF", where "DIFF" is
79 something like "<=0" or ">=0", etc.
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81 This module also supports the standard fsdb options:
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83 -d Enable debugging output.
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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.
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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.
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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.
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100 --help
101 Show help.
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103 --man
104 Show full manual.
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107 Input:
108 #fsdb title mean2 stddev2 n2 mean1 stddev1 n1
109 example6.12 0.17 0.0020 5 0.22 0.0010 4
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111 Command:
112 cat data.fsdb | dbrvstatdiff mean2 stddev2 n2 mean1 stddev1 n1
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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
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119 Input 2:
120 (example 7.10 from Scheaffer and McClave):
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122 #fsdb title x2 sd2 n2 x1 sd1 n1
123 example7.10 9 35.22 24.44 9 31.56 20.03
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125 Command 2:
126 dbrvstatdiff -h '<=0' x2 sd2 n2 x1 sd1 n1
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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
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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.
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137 Input 3:
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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
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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
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159 Output 3:
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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
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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
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197 (So one cannot say that they are statistically equal.)
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200 Fsdb. dbcolstats. dbcolcopylast.
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203 Copyright (C) 1991-2018 by John Heidemann <johnh@isi.edu>
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205 This program is distributed under terms of the GNU general public
206 license, version 2. See the file COPYING with the distribution for
207 details.
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211perl v5.30.0 2019-09-19 DBRVSTATDIFF(1)