Better Average Method

[Simon2001]

Hi

My heads hurting! I want to measure an ongoing monthly average based on data. I have a sheet where I track number of reports and for each report, I have a risk score.

For each month, I can easily measure the average risk score for the month but because each month the sample size changes, the average can be skewed. For example, January had 50 reports with an average of 3.2 but February had an average of 4.6 but from only 10 reports. From a quick glance, the risk goes up, which is right but then its hard to compare to the past.

I want a better way to track average risk score that isn't unduly affected by the sample size change each month. I did think MEDIAN but cant figure out how to do with multiple criteria.

Make sense?

Thanks

 

[Cubist]

You can do a weighted average. Put more weights on months that have more reports.

Book1
	A	B	C	D
1	Month	N	Avg	Weighted Average
2	Jan	50	3.2	3.20
3	Feb	10	4.6	3.43
4	Mar	25	3.5	3.45
Sheet3

Cell Formulas
Range	Formula
D2:D4	D2	=SUM(C$2:C2*B$2:B2/SUM(B$2:B2))

 

[Simon2001]

Thanks