# Help on programming different average calculations (©TapStack Pro).

#### Gerra

##### Member
Hi there, I need help on calculating different type of averages (I have guess how to work it out, but I want to be sure about it).

Assuming I have a session with 200 or more times:
Current average of 5/12/50/100 (What times to exclude, if any)
Rolling average of 5/12/50/100
Best average of 5/12/50/100
Standard deviation (Is this the mean of differences between times?)

Anything else that could be useful in a session summary page?
Any suggestion is more than welcome.

#### Gerra

##### Member
Is there any difference between average and mean (I don't have math-english skills)?

#### KJ

##### Member
Is there any difference between average and mean (I don't have math-english skills)?
Yes, they are.

#### MTGjumper

##### Member
For what it's worth, qqtimer seems to get rid of 5% of solves either side.

Also, sample standard deviation is calculated as sqrt[1/(n-1) * sum (x_i - (sample mean))^2] where the x_i's are the times, in this case. It might be easier to use sigma = sqrt[1/(n-1) * ((sum x_i^2) - n*(sample mean)^2)] instead, which is equivalent.

#### KJ

##### Member
I mean they are the same

#### pjk

Staff member
I've move this to off-topic, as it certainly isn't puzzle theory.
Hi there, I need help on calculating different type of averages (I have guess how to work it out, but I want to be sure about it).

Assuming I have a session with 200 or more times:
Current average of 5/12/50/100 (What times to exclude, if any)
Rolling average of 5/12/50/100
Best average of 5/12/50/100
Standard deviation (Is this the mean of differences between times?)

Anything else that could be useful in a session summary page?
Any suggestion is more than welcome.
I'd suggest reading up on Standard Deviation here.

Is there any difference between average and mean (I don't have math-english skills)?
Typically, no, in the context you're thinking. However, there are different means.

#### Gerra

##### Member
Thanks for the responses.
Now what if I averaging n element? What should I exclude from samples.
I'll simply exclude the best, ad the worst in the case of 5/12, but what about the session average, 50 and 100?

#### Gerra

##### Member
The question is language independent, though, I use Objective-C with a lot of C embedded.

#### Gerra

##### Member
I'll use the 5% (ceil) then.
It will exclude 2 elements from sample size of 21, hope it's right.