Cumulative Probability
Cumulative Probability
(OP)
I would be grateful if somebody reply back what is cumulative probability and how can I draw a graph for cumulative probability for around 20 datas?
Advice are appreciated.
Advice are appreciated.





RE: Cumulative Probability
TTFN
RE: Cumulative Probability
RE: Cumulative Probability
Thank you in advance.
RE: Cumulative Probability
To get the mu or alpha is more difficult (I generally use JMP 4 to get the values), but it is not impossible. Try searching the web for CDF, Cumulative Density Function, etc.. Otherwise, you will be forced to integrate the PDF from -infinity to X (as IRstuff pointed out). That is fairly straightforward to do using excel and a rough approximation technique (integral = area under the curve -> sum of slices [width times height]).
Good luck and keep us posted!
RE: Cumulative Probability
ASSUMING THE DATA SET IS NORMALLY DISTRIBUTED!!!! Use the NORMDIST function in Excel. You will need:
1) X (sample)
2) MEAN (AVERAGE on samples)
3) STANDARD DEVIATION (STDEV or STDEVP on samples)
4) CUMMULATIVE (1 or TRUE = CDF, 0 or FALSE = PDF)
You should be able to get it from there! Make sure you plot the data as an XY Scatter, NOT any type of line graph.
Good luck!
RE: Cumulative Probability
1- How can I interperet?
2- I want to email the graph online for you to see how I can do that.
regards.
RE: Cumulative Probability
2) Post the graph on a website and put a link to it in a response.
RE: Cumulative Probability
http://www.geocities.com/kingram56/post.doc
thnaks in advance.
RE: Cumulative Probability
http://groups.msn.com/Kingram/general.msnw?action=get_message&mview=0&ID_Message=2&LastModified=4675408859123392311
RE: Cumulative Probability
RE: Cumulative Probability
Perhaps, you would be more comfortable using a Survival plot.
Survival = 1- CDF
This will allow you to predict the amount of devices that will survive up to a leakage current (your measurement criteria).
Remember, all of this assumes that your data is normally distributed! You should also try to rerun your calcs based on a Weibull distribution (Weibull is a non-normal distribution). The only caveat is that Excel requires you to supply the alpha and beta values for the Weibull distribution, but cannot easily determine them using your data. Although the math is a bit tricky, you can certainly calculate them yourself (using Excel). Just do a websearch on the Weibull distribution, funciton, etc. and make your own worksheet to calculate the alpha and beta.
I hope that this helps / makes sense!
RE: Cumulative Probability
RE: Cumulative Probability
I will be back with the result later probably.
Shahram
RE: Cumulative Probability
http://groups.msn.com/Kingram/general.msnw?action=get_message&mview=0&ID_Message=3
thank you in advance,
I remain.
RE: Cumulative Probability
RE: Cumulative Probability
RE: Cumulative Probability
RE: Cumulative Probability
RE: Cumulative Probability
RE: Cumulative Probability
thank you in advance.
RE: Cumulative Probability
RE: Cumulative Probability
RE: Cumulative Probability
RE: Cumulative Probability
Did you re-run the data using a Weibull distibution?
What voltage do you take your leakage current reading?
RE: Cumulative Probability
I have tkaen the leakage current at 2V.