Message Number: YG6839 | New FHL Archives SearchFrom: Sukie Crandall

Date: 2001-08-31 18:10:00 UTC

Subject: deviation aspect -- on-set timing for adrenal growths

Just to explain about the most basics about slush factors in case a

few folks don't get that. In the study they had groups of on-set

ages in relation to how long before the altering had occurred. These

were NOT tightly clumped, at least for the most part (perhaps for

all, but I don't have the paper handy so am relying on memory).

That means that if you look at age A for neutering it is not defined

by a small age band years later in which adrenal growths appear, but

by a very diffuse blob. Look at age B for neutering and you imagine

that you will find another very diffuse blob for the on-set range.

If those two blobs have a wide range of OVER_LAP when adrenal growths

appear -- even with a few on the edge that don't) then the result is

that there is no real difference in on-set age range between age A

and age B -- until or unless later research clarifies or disproves

results. The few individuals on the edges may be different or they

could be just by chance, but for most there will not be a difference.

Now, say that age C's blob does not over-lap age A's or does so only

very slightly (or most are separated). Then you have a difference

that is discernable.

When a such factor is huge, trying to look at the difference between

two ages that are divided by a time frame smaller than the slush is

worthless.

Now, off-hand I can't recall what the +/- number was but I do recall

that it was HUGE and larger in either direction than the 6 month

increments in ages. If memory serves they later tried to run a line

through the means (averages) and form that arrived at about 3 and 1/2

years from neutering to onset of adrenal disease, BUT that was

actually something like 3 and 1/2 years PLUS OR MINUS 9 months

(though I seem to recall it being larger so even worse), If you look

at only the average and the slush factor then the RANGE seen for age

1 and 1/2 months at neutering is around 2 years and 10 and 1/2 months

to 4 years and 4 and 1/2 months, while the range for neutering at

age 6 months is from 3 years 3 months to around 4 years 4 and 1/2

months. Now, honestly, those of us who have had ferrets with later

adrenals know that the blob is even more diffuse.

You need to also look at the mode -- the FASHION, or most common age.

(Average is the ages added together and then divided by the total

number and that is the mean; median is the highest and lowest added

together and divided by 2.) If my memory serves the was about zip in

the way of tight clumping found so a person couldn't refine down to

the modes for two close age groups and see where those might differ.

Anyway, that is only a very most basic thing, but it's easy to

eye-ball to get a feel for what is going on before going further.