I have performance review data and scores (ranging from 1 to 4) for employees of a company. I need to show the company average over the past year. However, the employees were only ever reviewed for a few weeks in a row at a time.
Roger was reviewed from Jan 1 through March 1
Steve was reviewed from August 15 through September 15
Right now, I'm taking all of the reviews over the year (Jan 1 through Dec 31) and for each day I'm computing the average for that day. I then take all of those days and plot the average score for that day on a line graph with time on the X axis and score on the Y axis.
The problems I'm having are:
- there are gaps of time in these reviews (no one was reviewed in February, 20 people were reviewed in March)
- the higher performing employees may have been reviewed at one part of the year, and the lower performing employees at another
- when I plot this data the average produces a zigzag looking line chart. for example, day 1 the average is 3.4, but day 2 is 1.3. over time this looks like a lot of spikes.
So, where I'm at now is thinking of taking each employee as a "series" (where some series (employees) have data ranging for a few weeks, and some have data ranging a few months) and normalizing them together and computing the average of that normalization.
I'd greatly appreciate any help on this and the best way to present this data!