PS I removed several upper level outliers and this only reduced my stdev by about $0.10. Still 2sd from the mean is a negative.

- Thread starter derreckn
- Start date
- Tags standard deviation

PS I removed several upper level outliers and this only reduced my stdev by about $0.10. Still 2sd from the mean is a negative.

Min $0.01

Max $4.70

Mean $0.60

Stdev $0.57

May I ask if you have 12,000 why not just use the empirical distribution to calculate your probabilities?

I thought that emperical distribution was a normal distribution? I thought that was the bell shapped curve no?

How can I do this and/or what is the best wat to model this data?

How can I do this and/or what is the best wat to model this data?

Anyway, the quickest way to compute the empirical distribution is just find your ranking routine and rank the data points (from 1,,,n) the smallest data point is a 1 and so on. Then divide your ranks by your sample size n=12128.

Also excel has an exponential distribution function =EXPONDIST(X,Lambda,Cumlative) I'm not sure how I can use this. Does it return the probability of a particular value? If I summed a range of probabilities then would that give me the probability if that range?

Originally one concept was to use the price range between the fist stdev and second stdev (assuming a normal distribution). Knowing that an auction (based on past observations) has a point where the bidding will drop then I figured this would give my users a good chance at winning an auction that has made it to this price range.

So is there something like a 68-95-99.7 rule for an exponential distribution? What I did was counted the frequency of all the points of my data set. It shows that 43.3% of all observations fall between ($0.03-$0.34). Then it drops off and 34% fall between ($0.35-$1.00).

Based on the above my data reflects:

43.46% of all data falls within the range of $0.03 - $0.34.

The most frequent value (mode) is $0.17

After that 34.48% of the data falls with a range of $0.35 - $1.00

I'm not sure if this is the best way to go about this or not..