Finding Average of Signal

[AkshayHari]

Hello,

I have 60 seconds of voltage data that I acquired using a USB-6210. When I used the Statistics step to compute the mean/average of this signal, I got a certain value. However, when I ported the data to Excel and calculated the mean/average using Excel, I got a different value.

Any possible explanations?

Thanks,

Akshay

[amezam]

Good morning,

How different are the values? Are you comparing mean to mean and average to average, or main to average?

[AkshayHari]

SignalExpress Mean =345.805

Microsoft Excel Average =341.934

MATLAB Mean =317.7009

In SignalExpress I had my DAQ setup to take samples at a 1 kHz rate for 60 seconds (total of 60k samples).

What exactly is the difference between the mean and the average in this scenario?

Thanks,

Akshay

[amezam]

An average is a value of central tendency; it is the sum of the elements in that sample divided by the number of elements. The mean is one of the averages depending if it is arithmetic, geometric or harmonic, which are also different from the mode and the median of a set of values. The mode is the most repeated value, while the median is the middle value that separates the higher half from the lower half of data. So it depends on what value is it calculating or what reference is it referring to. Between Signal Express and Excel I would think maybe we have a difference because of decimals, but the one of Matlab is odd, do you know what is it calculating? 

[AkshayHari]

Thanks for the explanation.

Matlab describes its "mean" function as "Average or mean value."

Best,

Akshay

[amezam]

Hello Akshay,

That doesn’t say a lot. In all programs I guess you must be displaying the data as one array, right? I also checked for the Mean function in MATLAB, and the type seems to be arithmetic. Are you sure you’re using the same data in the three programs? I tested with some data in LabVIEW and Excel and I got the same value for the average.

Have a great weekend!