About free-hand wage lines
Drawing a job rate line free-hand is a simple method that works best when the points marking the job value and job rate of each job class form a straight line.
The job rate line should be drawn to fit the points on your scattergram as closely as possible. It is not necessary that any of the points actually be on the line as long as the line you draw best represents the pattern of points.
Calculating an average point
It is easier and more accurate to draw a straight line free-hand if you first calculate an average point. The average point is determined by taking the average of the job values and the average of the job rates for all male job classes in the representative group. The average job value and the average job rate - which become the average point - are then plotted on the graph. This average point becomes the pivot point through which any male job rate line would run.
These are the representative male job classes and the pivot point calculation:
Chart # 10
Average (Pivot) Point Calculation
|Representative Male Job Classes||Value (points)||Job Rate|
|Average (Pivot) Point||Average Job Value 1559 = 519.66 * 3 ||Average Job Rate $71.00 = $23.67 * 3&|
The male job rate line will run through the point on the graph where a job value of 520 * points(rounded from 519.66) and a job rate of $23.67 *intersect.
Plotting a wage line free-hand
Before using their computer's regression program, Space Toy Co. quickly plotted a male wage line using graph paper, a pencil and a clear ruler. As shown on the graph below, they:
- plotted the male job values and rates on the graph (the three squares in upper right corner of the graph);
- plotted the pivot point on the graph (the point midway between the three male jobs to the right, and the three female jobs to the left on the graph);
- positioned a clear ruler on top of the scattergram, making sure the straight edge passed through the pivot point;
- moved the ruler until the straight edge fit the data most closely;
- drew the line;
- plotted the female job values and rates on the graph (the three squares below the Female Jobs text box);
- identified the single female job below the line in need of an adjustment.
Chart # 11. Proportional Value Male Wage Line
Double-checking free-hand results using regression analysis
The above graph shows a single female job class paid below the Proportional Value male wage line and in need of an adjustment.
The Committee double-checked these results using Regression Analysis. More information on regression can be found on the next page.