Don Turnblade


  • 44/2357 = 1.73%

    Exact Binomial computation:
    97.98% confidence is 54/2367 or 2.28%

    Student’s T approximation of Binomial
    tinv(.05,2367-1)/(2*sqrt(2367) = 2.02%

    Correctly done approximate of Student’s T for binomial
    sqrt(5/(2367-3))/2 =2.30%

    From each of these 44/2367 or 1.73% is not enough to be 95% confident that binomial success/failure…[Read more]

  • I was trying to build you a more precise model to look at the confidence interval around your measurement 41/2373. However the closer I look at it the less hope I have for this measurement. I believe you have enough confidence for Marketing which only required a 66% confidence interval to make an inference. Business benefits from the 95%…[Read more]

  • Correction:
    Curve fit of tinv(.025,N-1)*sqrt(Odds(1-Odds)/N) = sqrt(Odds*(Odds-1)/N)*sqrt(5*N/(N-3))

    This reduces to sqrt(Odds*(1-Odds))*sqrt(5/(N-3)) ; using Tinv(.025,N-1)*sqrt(Odds(1-Odds)/N) is a reasonable approximation of dice behavior after N>=4. Generally below about N=20, one can directly compute the probability distribution for dice…[Read more]

  • Hitesh,

    The best advice I have when using statistical modeling is that if it fails a hypothesis test you do not have to think much. But, if it passes, that is when it is time to start thinking.

    Rule of thumb approximation for 95% confidence interval of tinv(0.025)*sqrt(Odds(1-Odds)/N) = sqrt(odds*(1-odds))*sqrt(5/(N-3))

    Your sample size N is…[Read more]

  • Hitesh,

    I do a lot of likelihood modeling for InfoSec work. I have some suggestions that may spark some useful thoughts. My notes are over focused on InfoSec/Risk Management concerns but may give you ideas to assist with odds based model building.

    Ideally, one would use half your data to fit the model and half your data to test the model.…[Read more]

  • In my view, this is an excellent summary. I also wish Healthcare success in process excellence as it is vital in so many areas at once. It also manages process risk at multiple levels at once.

    Risk Level 1: […]

  • I appreciate the approach for the basic Change Control Process implementation. As with any approach the first layer of a Pareto improvement looks for the first 20% of process improvements — such as credible […]

  • Don Turnblade changed their profile picture 3 years, 4 months ago

  • Don Turnblade changed their profile picture 3 years, 4 months ago

  • Alternative approach to project estimates is to use Queue Theory for the project.
    In effect a set of work units called Milestones is arriving over time to a team trying to resolve them.

    Staff loading needs […]

  • It turns out that humans have intuitive problems with estimated statistics: estimating extremes, center bias for averages, under reporting by half shameful items, over reporting twice honorable items, and small […]

  • Information Security vulnerability patching queues is a rather hot topic. Consider the time in queue of a critical vulnerability unpatched vs the mean time to exploit that vulnerability and harm the firm. Then, there is the cost of more staff to set up patching jobs, QA test them before releasing them to production. Is a faster team more…[Read more]

  • Drive storage arrays such as RAID stacks have large numbers of disks running in parallel that can fail and automated procedures that spin up hot swappable drives to replace these exist. But predicting purchase rates when cheaper drives fail faster versus purchase and failure rates when more expensive drives take longer to fail leads to a cost of…[Read more]

  • I think this article would benefit by adding a variable description and meaning. In the case that someone is new, it makes it clearer. Arguing a sophisticated point with someone in the know is makes it clearer.

  • Estimating the cost of quality even if imperfectly is one of the pivotal gates for improvement to win and sustain its good name, organizational trust and support. Being one of the most powerful tools, it is also the most obscured from view. The following is a humble contribution to the subject in a form your business lead, financial analyst and…[Read more]

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