Thanks - I'll PR.
G

On 2014-11-24 2:56 PM, Shoaib Sufi wrote:

Thanks Greg,

The intent and argument is much clearer with the text you refer to.

: )

On 24 Nov 2014 18:47, "Greg Wilson" <[email protected] <mailto:[email protected]>> wrote:

    Hi all,

    The 95% figure comes out of thin air - if you'd like to adjust it
    to 99%, and recalculate the overall odds of correctness, that
    would be fine.  In fact, I believe the original version of the
    text was something like:

    "...if there's a 95% chance of each line being correct, the odds
    of the whole function being right are only 41%.  Even if 99% of
    lines are correct, the odds are only 84%, which is still
    uncomfortably low."

    Do you think that would be clearer?

    Cheers,
    Greg


    On 2014-11-24 1:10 PM, Shoaib Sufi wrote:

    I didn't assert that it was the point.

    Thanks for the reference.

    On 24 Nov 2014 17:51, "Aron Ahmadia" <[email protected]
    <mailto:[email protected]>> wrote:

        From McConnell's summary in Code Complete:

        > Industry average experience is about 1-25 errors per 1000
        lines of code for delivered software.

        Of course, that's production code that has presumably been
        through far more testing and other forms of quality assurance
        than scientific code. The 95% number is just an assumption
        for an example, not a precise citation.  Greg may know of a
        better number for scientific code, but I don't think that's
        really the point of the exercise.

        On Mon, Nov 24, 2014 at 12:44 PM, Shoaib Sufi
        <[email protected]
        <mailto:[email protected]>> wrote:

            Hi Aron,

            What I mean is where does the assumption of a line of
            code being 95%
            correct come from.

            Thank you for helping me think more clearly about the
            question I wanted to ask.

            Best
            Shoaib



            On Mon, Nov 24, 2014 at 5:38 PM, Aron Ahmadia
            <[email protected] <mailto:[email protected]>> wrote:
            > It's a function of statistics, assuming each of the
            lines of code is an
            > independent distribution that is either correct or wrong.
            >
            > Given the input assumption (95% of all source code
            lines are correct as
            > written the first time), then the code is correct if
            the individual lines
> are all correct, which has probability P = 0.95^17. This is more correctly
            > rounded to 42%, but it's in the right ballpark :)
            >
            > On Mon, Nov 24, 2014 at 12:34 PM, Shoaib Sufi
            <[email protected]
            <mailto:[email protected]>>
            > wrote:
            >>
            >> Hi,
            >>
            >> At the bottom of:
            >>
            >>
            
https://github.com/swcarpentry/bc/blob/gh-pages/novice/r/04-cond-colors-R.Rmd
            >>
            >> It states:
            >>
            >> 'Our final heatmap function is 17 lines long, which
            means that if
            >> there's a 95% chance of each line being correct, the
            odds of the whole
            >> function being right are only 41%. Before we go any
            further, we need
            >> to learn how to test whether our code is doing what we
            want it to do,
            >> and that will be the subject of the next lesson.'
            >>
            >> Where is the reference for making a statement like
            that - i.e. %
            >> chance of errors based on function length.
            >>
            >> Thanks
            >> Shoaib Sufi
            >>
            >> _______________________________________________
            >> Discuss mailing list
            >> [email protected]
            <mailto:[email protected]>
            >>
            >>
            
http://lists.software-carpentry.org/mailman/listinfo/discuss_lists.software-carpentry.org
            >
            >




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    Software Carpentry |http://software-carpentry.org


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Dr. Greg Wilson    | [email protected]
Software Carpentry | http://software-carpentry.org

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