Cream of the Crop 1/Cream of the Crop 1.iso/BUSINESS/SPC11.ARJ/SPC_PN.PGH

Text File | 1991-08-26 | 9KB | 341 lines

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found_run
A RUN HAS BEEN FOUND
IN THE CONTROL CHART
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found_inc_trend
   AN INCREASING TREND HAS
BEEN FOUND IN THE CONTROL CHART
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found_dec_trend
   A DECREASING TREND HAS
BEEN FOUND IN THE CONTROL CHART
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found_shift_up
   A SHIFT UP HAS BEEN
FOUND IN THE CONTROL CHART
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found_shift_down
  A SHIFT DOWN HAS BEEN
FOUND IN THE CONTROL CHART
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found_cyclic
A CYCLE HAS BEEN FOUND
 IN THE CONTROL CHART
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found_freak_pattern
 A FREAK PATTERN HAS BEEN
FOUND IN THE CONTROL CHART
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found_stratification
 STRATIFICATION HAS BEEN
FOUND IN THE CONTROL CHART
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found_freak_point
  A FREAK POINT HAS BEEN
FOUND IN THE CONTROL CHART
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run1
                     WHAT IS A RUN?

RUNS -  This is any sequence of points for which a large
percentage fall on the same side of the mean.  This definition is
vague since many experts and source materials disagree on what
conditions to use.  This is conventionally identified.  The
following criteria are used to identify a freak pattern:


   (a) More than 7 (some say 5 and others say 8) points in a row on
       the same side of the mean.

   (b) Ten of 12 on the same side of the mean.
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run2
                    WHY IS A RUN UNUSUAL?

1. A chart which is in control should have points randomly scattered
   on both sides of the average.

2. A run indicates that some non-random or unnatural causes of
   variation are affecting the process.

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freak_point1
            WHAT IS A FREAK POINT (SPIKE)?


A freak point (or spike) is any point on the
control chart which lies outside of the Upper
or Lower control limits.
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freak_point2
          WHY IS A FREAK POINT UNUSUAL?


1. 99.9% of all points in a chart which is in control
   will fall within the Upper and Lower control limits.

2. A freak point indicates that some non-random or unnatural
   causes of variation are affecting the process.
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freak_point3
         WHAT DOES A FREAK POINT MEAN?


1. Freak points mean that something very unusual
   has happened in the process.

2. A freak is produced by an outside unusual cause.

3. It isn't present for very long.

4. Freaks are the easiest chart patterns to find
   the assignable cause for.
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freak_point4
          A FREAK POINT CAN BE GOOD OR BAD!

1. A freak point above the Upper Control Limit is BAD.
   This means that some un-natural cause(s) have forced
   the number of defects/defectives in your process to
   momentarily increase.

2. A freak point below the Lower Control Limit is GOOD.
   This means that some non-random cause(s) have forced
   the number of defects/defectives in your process to
   momentarily decrease.
@
freak_pattern1
                 WHAT IS A FREAK PATTERN?

FREAK PATTERN  -  This is any sequence of points for which a
large percentage fall more than a given amount away from the mean.
This definition is vague since many experts and source materials
disagree on what conditions to use.  The following criteria are
used in this software to identify a freak pattern:


   (a) 2 out of 3 points in a row outside of the 2 sigma limits.

   (b) 4 out of 5 points in a row outside of the 1 sigma limits.
@
freak_pattern2
          WHY IS A FREAK PATTERN UNUSUAL?


1. Very few points should fall outside the Warning Limits.

2. Something in the process has drastically changed for
   a short period of time.
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shift_up1
               WHAT IS A SHIFT UP?

1. Several consequetive points tending to be below the
   average followed by several more consequetive points
   tending to be above the average.

2. Something has acted on the process and changed
   the distribution.
@
shift_up2
               WHY IS A SHIFT UP UNUSUAL?

1. A chart which is in control should have points randomly scattered
   on both sides of the average.

2. A shift up indicates that some non-random or unnatural causes of
   variation are affecting the process.
@
shift_up3
              WHAT DOES A SHIFT UP MEAN?

1. Something new has been introduced into the process.

2. Something different from what you've been doing or using before.

3. This new element changes the whole process.  At least for awhile.

4. You have shifted the center of the distribution.
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shift_up4
            A SHIFT UP IS BAD!!

Some unnatural cause(s) have drastically increased
the number of defects/defectives in your process.
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shift_down1
               WHAT IS A SHIFT DOWN?

1. Several consequetive points tending to be above the
   average followed by several more consequetive points
   tending to be below the average.

2. Something has acted on the process and changed
   the distribution.
@
shift_down2
              WHY IS A SHIFT DOWN UNUSUAL?

1. A chart which is in control should have points randomly scattered
   on both sides of the average.

2. A shift indicates that some non-random or unnatural causes of
   variation are affecting the process.
@
shift_down3
             WHAT DOES A SHIFT DOWN MEAN?


1. Something new has been introduced into the process.

2. Something different from what you've been doing or using before.

3. This new element changes the whole process.  At least for awhile.

4. You have shifted the center of the distribution.
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shift_down4
            A SHIFT DOWN IS GOOD!!

Some non-random cause(s) have drastically decreased
the number of defects/defectives in your process.
@
cyclic1
               WHAT IS A CYCLE?

1. A sequence of several consequtive points which tend
   over time to regularly rise and fall.

2. A cycle may have several deviations from this pattern;
   however, the overall tendancy is for a regular rise
   and fall pattern.
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cyclic2
               WHY IS A CYCLE UNUSUAL?

1. A chart which is in control should have points which change
   randomly with no particular tendancies.

2. A cycle indicates that some non-random or unnatural causes
   of variation are affecting the process.
@
cyclic3
         A CYCLE IS GOOD AND BAD!?

Some un-natural cause(s) are forcing the number of
defects/defectives in your process to consistently
increase and then decrease over time.

This means that your process is both capable of
producing a relatively low number of defects/defectives
as well as a relatively high number of defects/defectives.
@
cyclic4
                 CYCLIC PATTERN

A cyclic pattern is caused by the same thing happening
at the same time over and over again.  Common causes
of cyclic patterns include:


   1. Defective equipment

   2. Fluctuating electricity

   3. Weather conditions such as humidity, temperature,
      and pressure

   4. Human Factors
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cyclic5
       CYCLIC PATTERNS & THE HUMAN FACTOR

1. The most common cause of cyclic patterns is the human
   factor.

2. Do not forget to look at the human factor when looking
   for causes.

3. Shift changes and new hires show up on the charts.

4. Being tired or unfamiliar with with job can cause some
   pretty strange chart patterns.
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stratification1
                    WHAT IS STRATIFICATION?

STRATIFICATION  -  Sometimes referred to as "hugging the center
line."  This is any sequence of points for which a large percentage
fall less than a given amount away from the mean.  This definition
is vague since many experts and source materials disagree on what
conditions to use.  This is conventionally identified.  The
following criteria are used to identify a stratification pattern:

   (a) Ten or more points in a row which are within the 1 sigma
   limits.
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stratification2
    WHY IS STRATIFICATION UNUSUAL?


1. The points are unnaturally quiet.

2. There is too little variation.

3. If the process is in control the points
   should be more spread out.
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inc_trend1
        WHAT IS AN INCREASING TREND?

1. A sequence of several consequtive points which tend
   over time to rise.

2. An increasing trend may have several downward steps;
   however, the overall tendancy is for upward steps.
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inc_trend2
           WHY IS AN INCREASING TREND UNUSUAL?

1. A chart which is in control should have points which change
   randomly on both upwards and downwards with no particular
   tendancies.

2. An increasing trend indicates that some non-random or unnatural
   causes of variation are affecting the process.
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inc_trend3
       AN INCREASING TREND IS BAD!!

Some un-natural cause(s) are forcing the number of
defects/defectives in your process to consistently
increase over time.
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dec_trend1
         WHAT IS A DECREASING TREND?

1. A sequence of several consequtive points which tend
   over time to fall.

2. An decreasing trend may have several upward steps;
   however, the overall tendancy is for downward steps.
@
dec_trend2
            WHY IS A DECREASING TREND UNUSUAL?

1. A chart which is in control should have points which change
   randomly on both upwards and downwards with no particular
   tendancies.

2. A decreasing trend indicates that some non-random or unnatural
   causes of variation are affecting the process.
@
dec_trend3
        A DECREASING TREND IS GOOD!!

Some non-random cause(s) are forcing the number of
defects/defectives in your process to consistently
decrease over time.
@