I think maybe you meant to send this to edstat instead of to me.
>The supervisor's recommendation doubtless arises from the advice to be
>found in many contemporary textbooks in elementary statistics: If the
>(raw) distribution be symmetrical, the mean and standard deviation are
>adequate for descriptive purposes and are to be preferred. If the
>distribution be skewed (at least, skewed enough to be visible and worth
>worrying about) the median and quartiles (or median and hinges: a box
>plot) are preferred, because while mean & s.d. CANNOT convey any
>information about asymmetry in the distribution, median and quartiles
>MAY convey such information (if the quartiles are unequally distant from
>the median).
>
>Whether the supervisor's advice was "sage" (or even "good") in the
>current context I cannot say, since there is nothing in the post (as
>received from Stan -- I haven't seen Tony's original) to indicate what
>purpose lay behind the decision, nor what further analysis(es) might be
>contemplated that might use the summary information (rather than the raw
>data).
>
>On Fri, 25 Jul 2003, Stan Brown wrote:
>
>> In > sci.stat.edu, Tony <[EMAIL PROTECTED]> wrote:
>>
>> >One of these statistics collected was how many weeks did it take to
>> >fill a vacancy. ... The reply from her supervisor was "if the
>> >results are normally distributed then use the mean otherwise use the
>> >median". I am sure this is sage advice, but why?
>
>Not so sure the advice was "sage"; and in any case she SHOULD have
>said, "If the results are approximately symmetrical and unimodal", since
>NO results are ever normally distributed...
>
>> >I would have thought that if the distribution was normally
>> >distributed then the mean and the median would be roughly similar
>>
>> Not just roughly similar, but identical. The same is true for any
>> symmetric distribution, whether normal or not.
>>
>> >since the normal curve has the frequency distributed around
>> >the mean.
>
>As Stan more gracefully pointed out, this subordinate clause is without
>useful meaning.
>
>> > My further thinking about this was that for any
>> >distribution the mean will always be the upper bound of the median.
>> >Is this correct?
>>
>> No.
> < snip, discussion of asymmetry >
>
>Cheers! -- DFB.
> -----------------------------------------------------------------------
> Donald F. Burrill [EMAIL PROTECTED]
> 56 Sebbins Pond Drive, Bedford, NH 03110 (603) 626-0816
>
>
--
Regards,
Stan Brown, Oak Road Systems, Cortland County, New York, USA
[EMAIL PROTECTED]
http://oakroadsystems.com
--
Regards,
Stan Brown, Oak Road Systems, Cortland County, New York, USA
[EMAIL PROTECTED]
http://oakroadsystems.com
.
.
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