This is the SPC chart for Individual observations (I) and Moving Ranges (MR). It can be used to study short-term process variability. It allows analysis in multiple stages, e.g. when we have data for many machines, subprocesses, periods etc.

Using the last option named "Select type of diagram" one can create an Individual observations (I) chart or I-MR an Individual observations (I) and and Moving Range (MR) chart. By default, the option is set to "I-MR Chart".

The tool works on-line. Enter the data into the "Data in txt format" text area, where a single row contains one, two or three data (one, two or three columns). The first row can be the data header. For example, you can copy 1-3 columns from Excel and paste into the data window.

If the user does not provide her (his) own data, the program create a chart from the default data displayed in the "Data in txt format" window. The default data has 3 columns. The diagram is created based on data from the 1st column relative to the 3rd column. If you are curious how the change in the reference column affects the diagram, change the option "Levels in column(s)" from "3" to "2" or "-".

If the user provides only one data column, one needs to change the option "Levels in column(s)" to "-" to avoid data error. Similarly to avoid data error in the case of two columns given by the user, one needs to change the option "Levels in column(s)" to "2" or "-".

Data can be copied e.g. from Excel, but also entered manually. The minimum number of data is 2 (2 data rows). In addition program can draw reference lines (see option "Reference lines"), which can be switched on/off, and establish stages based on 2nd or 3rd column or combination of both of them.

Regardless of the language chosen, the diagram is formatted according to the English convention. This applies to the format of numbers and descriptions.

The data must be in one of two formats:

  
• Decimal separator ",". Groups separators in numbers are unacceptable. The correct data is for example 1,234 or 34456,12. Invalid data 34 456,12 - blank space not allowed.
• Decimal separator ".". Groups separators in numbers are unacceptable. The correct data is e.g. 1.234 or 34456.12. Invalid data 34,456.12 - no comma as group separator or 34 456.12 - blank space not allowed.

The data structure must be as follows:

  
• 1st column - numerical data, e.g. dimensions of parts, invoice processing time, etc.
• 2nd column (optional, called stage) - text data, e.g. machine name etc.
• 3rd column (optional, called stage) - text data like in 2nd column.     Additional stage relative to which we want to analyze something, e.g. line name, time of the day, etc.
• 2nd and 3rd column are logically the same. Theoretically there can be many combination of stages. Usually, combination of 3 levels are used maximally.    I offer combination of 2 levels, which is enough in 90% of cases.

An important element of the SPC card are the mean (central line), control limits and tests used to detect special causes. Using the "Format SPC chart" form, you can activate the execution of various elements (in the "Execute" column). Each element can be hidden or shown (in the "Hide/Show" column) if it has been activated.

Hiding or showing elements of the SPC chart is particularly helpful in case of special causes tests, because some points indicate several special causes marked with numbers from 1 to 8 (correlated with the number of test). For I chart one can select 8 tests, however for I-MR chart (bottom diagram) one can perfom only 1st. test.

In the Minitab program and in my program 8 tests (rules) are distinguished, in which the "K" counter can be changed and the meaning of which is the following:

• Test 1 - Point > K * standard deviation from the mean (center line), by default K=3.
• Test 2 - K points in a row on same side of the mean (center line), by default K=9.
• Test 3 - K points in a row in ascending or descending order, by default K=6.
• Test 4 - K successive points alternating up and down, by default K=14.
• Test 5 - K of K+1 consecutive points > 2 * standard deviation from the mean (center line) on the same side, by default K=2.
• Test 6 - K of K+1 consecutive points > 1 * standard deviation from the mean (center line) on the same side, by default K=4.
• Test 7 - K following points within the area of +/-1 * standard deviation from the mean (center line) on each side, by default K=15.
• Test 8 - K following points in the area > 1 * standard deviation from the mean (center line) on each side, by default K=8.

At the moment in case of transferring SPC chart to another program, I can only offer a screenshot. However, the diagrams are made in SVG vector format.