>> Can you comment on how other researchers compute efficacy and if
>> there is an agreed method or if varying methods are used.

> The book mentions that efficacy can vary depending upon season--I
> also observe this.  Also may vary with temperature, colony size,
> proportion of sealed brood, etc.

True, but the question is how to measure that efficacy, especially if
the treatment(s) take place over time.  During that time mites are
hatched and die natural deaths, too, as you pointed out when I was
wrestling with this question last.  I believe you suggested that I could
not prove I killed them and they the mites I thought I killed might have
died anyhow.

> One major issue is whether a treatment has a delayed effect.  For
> example, if a treatment suppresses the mating success of mites, then
>  one might not see an immediate result, but would see a longer-term
> suppression of mite levels.

That is the claim made for some formic fumigation methods and which was
illustrated in an Ontario test in which dead male mites were observed at
a higher rate than in controls suggesting a probable mating failure for
that batch of females.

> Then the question is how to estimate the actual number of mites in a
>  hive at any time.

Yes.  That is one question, but what is the baseline for comparison?  I
had assumed an absolute measure, computed by counting all the mites
dropped until almost none were left according to convincing evidence.
(That's another debate).

> Then there is the issue of direct vs indirect methods of
> measurement. We've been through this before, and we clearly
> disagree.

Not so much as you might think.  If there is disagreement, it is only on
how much certainty we can ascribe to any method. How much certainty and
precision we really need in such a fuzzy topic is another debate once again.

> Any measurement of mite fall is an indirect measurement, depending
> upon many variables, and can vary greatly from day to day, despite
> the actual mite population or infestation rate of the adult bees
> being relatively constant over the same period.

The cumulative total, however is the cumulative total.  Baring errors
and losses of dropping mites, there is little debate there, I hope. As
for the residue count of surviving mites after treatment and cleanup, we
can only use clues and deduction.

> ...the researcher planned to use the same miticide for the clean up
> drop (to determine remaining mites in the colonies) as the miticide
> being tested, which I find fault with.

That is really funny in a sad sort of way.

> To me, the bottom line is to determine the final effect of any
> treatment upon mite population growth over time.  I prefer to measure
> after at least three mite reproductive cycles (about 51 days).

Yeah.  My instinct was to just count how many mites total dropped and
then compare to what could be killed in cleanup with a known effective
method after the treatments, but I am beginning to realise that everyone
has his or her own idea of what efficacy is and how to measure.

What stimulated this was Medhat's mention in regard to that hops stuff
and he has yet to comment.

I had thought Jerry would have grasped this nettle by now, too.

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