I'm a complete noob when it comes to statistics, so please excuse my lack of standard terminology. I think my question might be related to normalization, but please re-tag if I'm wrong.
I'm a programmer by trade, and I've been tasked with creating a chart which shows how the number of errors in a data set change from month to month. Unfortunately we don't have a statistician in-house to help me figure it out...
The data is as follows: Each month, a number of items are entered into a database. These items are checked for errors, and the errors are also entered into the database. Each item can have multiple errors of different types, and the number of items added each month can vary a lot.
How can I show how the error frequency changes from month to month?
It doesn't "feel" right to show a percentage of errors/number of items since there can be multiple errors for each item. The chart also needs to be easy to understand even by people with no background in statistics, so something as close as possible to the real values or percentages would be good.
An example of the data with total number of errors per month:
Month Errors Items ===================== March 208 2027 April 276 1304 May 609 1721 June 167 1561 July 268 513
The errors for March could be broken down like this:
Type Errors ================== Type 1 2 Type 2 43 Type 3 93 Type 4 0 Type 5 1 Type 6 0 Type 7 4 Type 8 0 Type 9 22 Type 10 0 Type 11 43