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ptc-43103781-Visitor
1-Visitor
March 27, 2012
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What is a Frequency Chart, how to generate?

  • March 27, 2012
  • 1 reply
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Moderator: Please delete if this type inquiry is not appropriate. Just trying to tap into the vast knowledge base here......

Have an assignement coming up where we will have to classify a set of data via a frequency chart.

I intend to implement in Mathcad, but have never heard about this frequency scale on the chart. The Professor gave no references we could look up on the origin of the chart. He said he would give us instructions in Excel at a later date on how to build such a chart. Am curious if anybody here would be familiar with such a frequency plot and implementation in Mathcad?

From what I could see in class, the frequency scale on the absicissa starts at .01, with 50 in the middle of the axis and ends at 99.99. I'd say on this scale 1 would be about a third of the way to 50 and 20 at 2/3 of the way, then symetry on the other side of 50 with 70 at 1/3rd of the way to 99.99 and 99 at 2/3rd of the way.

Anybody familiar with this "frequency" scale and its origin/background and how to generate a graph based on this scale from a set of data pairs?

Thank you.

Best answer by MichaelH

Mathcad does not specifically have a graph like this as far as I know, but you can make one that has similar characteristics by using the Weibull distribution functions. The x-axis will be in standard deviations from the mean, but you can easily convert this to percentiles using these functions.

There is a sample worksheet (a.k.a. "Quicksheet") showing how normal distribution functions are related to percentiles under the "Normal Distribution" topic. It should not be too much effort to convert this into a Weibull plot.

1 reply

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MichaelH1-Visitor
1-Visitor
March 27, 2012

Many types of data distributions fit a "Gaussian" (also called "Normal") distribution, which sounds like what you are looking for. If the outcome of an event has only two possibilities (such as heads or tails from a coin toss), it is called the "Binomial" distribution.

You can use the "Histogram" function in Mathcad to "bin" the data and see how it fits.

Any introductory book on statistics should cover this in sufficient detail.

P
ptc-43103781-VisitorAuthor
1-Visitor
April 2, 2012

I found freeware that will generate the plot I need against this lognormal scale.

http://www.zonums.com/lnpp.html

Just not sure about the theory behind it for duplicating in Mathcad. Was hoping somebody may have done it with Mathcad before.

Otherwise, looks like this freeware will do.

M
MichaelH1-VisitorAnswer
1-Visitor
April 2, 2012

Mathcad does not specifically have a graph like this as far as I know, but you can make one that has similar characteristics by using the Weibull distribution functions. The x-axis will be in standard deviations from the mean, but you can easily convert this to percentiles using these functions.

There is a sample worksheet (a.k.a. "Quicksheet") showing how normal distribution functions are related to percentiles under the "Normal Distribution" topic. It should not be too much effort to convert this into a Weibull plot.

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