Question

I am trying to build a windows phone 7 app with vb.net

And i need to clear my listbox:

932 100 592 21 924 641 200 1230 5200 842 951 658

I would like to remove the “wrong numbers” because i want to get the average.
In this case the wrong numbers are:
too low: 100, 21, 200
too high: 5200

I just figure out a way to do this

For each items in listbox 
 calc the avarage
Next

for each item in listbox
 if item < avarage/2 then
 remove item
 end if
 if item > avarage*2 then
 remove item
 end if
next

for each item in listbox
calc the avarage
next

Answer 1

This is how to find outliers in a series of values:

1. Compute the mean of all the points: m

2. Compute the standard deviation: s

3. For each point with value v if abs(v - m) > s then v is an outlier.

Here is the pseudo code to do that:

m = sum(v0, v1, ...) / N
diff = sum((v0-m)^2, (v1-m)^2, ...) / N
s = sqrt(diff)

for each value v
    if abs(v - m) > s then
        remove v
    end if
end for

Now, you have M values and you can compute their average:

average = sum(V0, V1, ...) / M