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Original file (SVG file, nominally 630 × 629 pixels, file size: 39 KB)

Summary

Description
English: Example en:u-chart for a process that experienced a 1.5σ drift starting at midnight.
Date
Source Own work
Author DanielPenfield

Creation technique

  1. Simulate process observations using en:perl, output to file.
  2. Read file into R, use qcc package to render control chart.
  3. Save to PDF.
  4. Import into en:Inkscape, save to SVG.
#!/usr/bin/perl -w

use strict;
use Math::Random;

my %shiftSchedule = (
    "first" =>  { "start" =>  6.00, "end" => 14.00 },
    "second" => { "start" => 14.00, "end" => 22.00 },
    "third" =>  { "start" => 22.00, "end" =>  6.00 }
);
my $shift = "third";         # shift to monitor
my $inspectionRate = 1 / 2;  # every 1/2 hour
my $drift = 1.5;             # sigma drift to simulate
my $m = 25;                  # samples in control chart setup
my $target = 0.10;           # fraction nonconforming target

my $c = $target;
my $n = 48;                  # observations per sample
my $hour;
my $i;
my $minute;
my @observations;
my $observation;
my $setupM = $m;

print "timestamp sample sampleSize observation phase\r\n";

for ($i = 1; $i <= $m; $i++) {
    @observations = Math::Random::random_poisson($n, $c);
    $observation = 0;
    map { $observation += $_ } @observations;
    printf "     0:00 %6d     %6d          %2d setup\r\n", $i, $n, $observation;
}

$m = $shiftSchedule{$shift}{"end"} - $shiftSchedule{$shift}{"start"};
if ($m < 0) {
    $m += 24;
}
$m /= $inspectionRate;
for ($i = 1; $i <= $m; $i++) {
    $hour = int($i * $inspectionRate + $shiftSchedule{$shift}{"start"});
    if ($hour >= 24) {
	$hour -= 24;
    }
    $minute = ($i & 0x1) ? (60 * $inspectionRate) : 0;
    if ($i >= (0.25 * $m)) {
	if ($i < (0.75 * $m)) {
	    $c = $target + ($drift * $target / (0.5 * $m)) * ($i - (0.25 * $m));
	} else {
	    $c = $target + $drift * $target;
	}
    }
    @observations = Math::Random::random_poisson($n, $c);
    $observation = 0;
    map { $observation += $_ } @observations;
    printf "    %2d:%02d %6d     %6d          %2d monitoring\r\n", $hour, $minute, $setupM + $i, $n, $observation;
}
 
This chart was created with R by v.

Licensing

I, the copyright holder of this work, hereby publish it under the following licenses:
w:en:Creative Commons
attribution share alike
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
You are free:
  • to share – to copy, distribute and transmit the work
  • to remix – to adapt the work
Under the following conditions:
  • attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
  • share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.
GNU head Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License.
You may select the license of your choice.

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16 January 2010

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Date/TimeThumbnailDimensionsUserComment
current21:52, 16 January 2010Thumbnail for version as of 21:52, 16 January 2010630 × 629 (39 KB)DanielPenfield{{Information |Description={{en|1=Example en:u chart for a process that experienced a 1.5σ drift starting at midnight.}} |Source={{own}} |Author=DanielPenfield |Date=2010-01-16 |Permission= |other_versions= }} [[Category:Con

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