Weighted Average

I am looking for an explanation of a weighted average as it would be used in a process. I am familiar with how it is used for grading in education, but what type of process would need to use a weighted average?

A weighted average in my business (Petroleum Measurement) is using a process condition to do the average.

For example we do a Volume Weighted Average for Temperature. We take the Temperature every Barrel and add it to a total. Then we divide the total temp by the total number of Barrels that have passed.

We could do the same thing by taking a temp sample every 10 seconds but then the average temperature would be a time weighted average as it would be based on a time.

Make sense?

I don't think that is a weighted average Bullzi. That is just average.

I think it would be a weighted average if you have different barrel sizes. Say size A and size B which is 2xA.

You get 10 measurements from each, so 20 total. But because barrel B is bigger, you "weigh" it more in the average temp. So you take average A and 2x average B to get a total weighted average.

Me thinks... Correct me if I am wrong .

if you google "weighted average" you will get lots of examples.

regards,
james

Weighted average depends on the application. Since you are using the term "weighted", it must mean something other than just average.

If you are using it in a process control application,it can be used a couple of similar ways. You could do it according to an equations, such as Val = (lastVal * K + newVal) /(K+1). That would give you a measurement that dampens out rapid transitions or noise. That is an average that is "weighted" towards the more recent measurements. Another type of average that is sometimes used is to keep a total of the last X measurements & do a straight average. Each time you take a measurement, drop off the oldest measured value. This isn't "weighted, but it is an average that again, smooths out transitions or noise.

The bottom line is determining what you are trying to achieve & what makes sense for your application.

Vel - What you describe is a moving average. I use that frequently for signal smoothing. Weighted Average needs an array of values equal to the number of samples taken over sampling period. i.e. 60 samples, 60 weights.

James - I get lots of examples from google, but all using Grades or scores as examples. Nothing process related.

Bone - OK thats an example that at least is plausible and lets me visualize a potential use.

Sure would like an example that someone in process has actually using.

We use a weighted average to calculate our daily scrap percentage.

(Pieces processed * Scrap Percentage) for each part number, add it all together and divide by # different part numbers packed that day.

boneless said:

I don't think that is a weighted average Bullzi. That is just average.

I think it would be a weighted average if you have different barrel sizes. Say size A and size B which is 2xA.

You get 10 measurements from each, so 20 total. But because barrel B is bigger, you "weigh" it more in the average temp. So you take average A and 2x average B to get a total weighted average.

Me thinks... Correct me if I am wrong .

Click to expand...

I agree. A weighted average is a mean that is calculated with greater magnitude applied, hopefully for some legitimate reason, to certain samples as compared to other samples.

OK Scrap percentage. thats something i can get my head around.
Thanks