Mean when value = 0
Message posted by Snorkyller (via 206.99.185.180) on October 3, 2001 at 5:09 PM (ET)

I have to calculate the mean of a motor speed, considering the times of values change.
But I have a little problem.
I show below how I procede:

Speed | Time | A | B
-----------------------------
34 | 4 | .02 | 0.6634
37 | 10 | .05 | 1.8049
15 | 2 | .01 | 0.1463
0 | 99 | .48 | 0
14 | 87 | .42 | 5.9415
0 | 3 | .01 | 0
-----------------------------
205 | 1 | 8.5561

A = Time / 205
B = Speed * A
So i get the mean 8.5561

My problem is that when the speed is 0, the time is not
considerated because we get 0 in B with any value of time. So, if the motor stop for 99 or 3 sec., I have the same result even if the 2 motor stops doesn't take the same time...

How should I procede to make the motor stops(speed=0)duration affect correctly the mean.

Thank you!

READERS RESPOND:
(In chronological order. Most recent at the bottom.)

Re: Mean when value = 0
Message posted by Tomi (via 154.32.143.47) on October 5, 2001 at 10:08 AM (ET)

Mean speed = (Total distance) / (Total time)

I would multiply speed by time first, to get the distance travelled in each section of the journey. Then I would add them together and finally divide by the total time (205).

The reason you are getting the zero values is because the distance travelled in bith cases is zero, because the speed is zero.

Although you are unhappy about this, it is all accounted for by the addition of the times to get 205. If your 99 second stop was only 9 seconds, the divisor would be 115 instead of 205 and the mean speed would therefore be much higher.

Get it?