# A program to prepare Levey-Jennings charts with integrated software.

A program to prepare Levey-Jennings charts with integrated software

We have tried some of the special commercial microcomputer programs available for drawing Levey-Jennings charts and found them difficult to use in addition to being expensive. That led us to develop a simple program to prepare these charts, based on the popular Framework II software (Ashton-Tate, Torrance, Calif.) for IBM PCs. Similar programs may be created with such integrated software as Lotus Symphony and Appleworks.

Framework's capabilities include word processing, database management, spreadsheets, telecommunication, and graphics. Our program combines a spreadsheet with graphics.

Only the control test values are entered. Then one presses IBM PC function key F5, and the standard deviation, the mean, and the mean 2 SD are automatically calculated in the spreadsheet. Next, function key F6 is pressed to label the portion of data that need to be drawn--perhaps a few days of test values or a month's worth. Finally, Framework's graphics program generates the chart.

Five columns are used in the spreadsheet (see Figure I). On the top row, cell A1 is a heading. Cell B1 contains instructions to calculate the standard deviation; the instructions are written out as @STD (B3:B33). Cell C1 contains instructions to add 2 SD to the mean: (D1 B1 B1). Cell D1 contains instructions for calculation of the mean: @AVG (B3:B33). Cell E1 contains instructions to subtract 2 SD from the mean: (D1-B1-B1).

The cells C1, D1, and E1 are copied below in their columns down to the last row, line 33, exactly as is shown in Figure I. Through this repetition of calculated numbers, the framework of the Levey-Jennings chart is drawn--the continuous horizontal lines that represent the mean and the mean 2 SD. In Figure II, the spreadsheet has been filled out with BUN control values and calculated standard deviation limits.

For a clean initial spreadsheet display, zeroes are entered as the first few control values, and key F5 is touched. Zeroes then will appear in columns A though E.

The program is not only simple but also quite flexible. One can draw charts with multiple control values for each day, to compare the quality control performance of two or more technologists, for example. Figure III shows a single-value chart, and Figure IV shows a multiple-value chart. The multiple values are entered in extra new columns between columns B and C of the spreadsheet. The average of multiple daily values can also be used. Color is a useful option when charts track more than one set of values.

New control values may be entered while retaining old standard deviation limits, such as those of the previous month. To accomplish this, you simply omit pressing the key F5 after entering the new values, so that the standard deviation and mean will not be recalculated. Different standard deviation limits can also be set or added--2.5, 2 and 3, and so on.

Of course, the charts can be given whatever titles and subtitles one chooses, including a hospital or laboratory name and a description of the procedures for which QC is being graphed.

Multifunction software such as Framework II is often a valuable ally to the busy manager. Clinical laboratories and labs specializing in industrial quality control require diverse programs to meet needs that vary from writing test procedures to maintaining inventories of chemicals, from budgeting to performing linearity checks, and from writing letters to preparing schedules. We have extended the uses of such software to develop customized Levey-Jennings quality control charts.

Bear in mind that our specific program is meant to be used with Framework II software. Interested readers can obtain a copy of our program by sending a diskette and a stamped, self-addressed envelope to the author at the Department of Pathology, Wake Forest University, Bowman Gray School of Medicine, Winston-Salem, N.C. 27103.

Table: Figure I

Programming the spreadsheet to generate L-J quality control charts

Table: Figure II

Spreadsheet after entering values and calculating standard deviation limits

Table: Figure III

A BUN quality control chart

Table: Figure IV

BUN quality control by technologists A and B