Date:         Fri, 31 Jul 2020 13:43:49 -0700
Reply-To:     David McNeely <davmcneely40@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David McNeely <davmcneely40@GMAIL.COM>
Subject:      Re: Project Farm Battery Test
Comments: To: Jack R <jack007@comcast.net>
In-Reply-To:  <000501d66763$d9472530$8bd56f90$@net>
Content-Type: text/plain; charset="UTF-8"

Well ......... .  Anyone who knows anything about experimental design knows
that this "experiment" is deeply flawed.  Every time you measure something,
the value you get is an estimate.  It takes a series of measurements of
each of a sample of items to give a mean value for items of that type.  One
measurement is not a fair estimate.  Typically, in an experiment to compare
two different sorts of things, one wants a mean value from measuring some
20 individuals of each sort.  Then one can calculate a mean and standard
error.  Roughly, a large overlap in standard error would then suggest that
the two sorts are no different from each other.  No or a small overlap in
standard deviation would suggest that the two sorts of things are
different. It's a bit more complicated than that, but that's the idea.
Getting two different values from measuring one individual of each sort
like was done in this "experiment" might be within experimental error.
Next time the experiment is done, the values might be reversed between the
two sorts.  Experimental design theory generally suggests that it takes 20
individual measurements, one measurement of each of 20 individuals, to give
a fair estimate of the true mean value.

Bottom line:  Based on this "experiment," I do not know that one of the
battery brands is better than another.  In fact, if one Wal-Mart battery
were compared with one "identical" other Wal-Mart battery, the same
difference between the two as between the Wal-Mart and the Autozone battery
might show up.

You can take all this for whatever you deem it to be worth, just as I will
take the "experiment" in the video for what I deem it to be worth.

mcneely

On Fri, Jul 31, 2020 at 10:56 AM Jack R <jack007@comcast.net> wrote:

> Very educational.
>
> https://www.youtube.com/watch?v=h7rTcBanpMk
>
>
>
> Interesting independent test of batteries
>