StatN5.txt
Dear Scientific Friend,
Tentative efforts lead to tentative outcomes. Therefore give
yourself fully to your endeavors. Decide to construct your
character through excellent actions and determine to pay the price
of a worthy goal. The trials you encounter will introduce you to
your strengths. Remain steadfast ... and one day you will build
something that endures; something worthy of your potential.
Epictetus
To know and not to do -- is not to know.
Chinese proverb
===============================================
Subject: The PRESUMED "failure" of plus-prevention.
Re: Conditions for a potentially SUCCESSFUL plus-prevention
study among motivated pilots.
Re: Approximate values (but realistic) are used in these
calculations.
From the discussion with Judy, and other not-cautious ODs,
they LOVE to impress the child and parent with "Best Visual
Acuity". What does this mean in "Practice?" It means this:
The child who has a CONFIRMED visual acuity of 20/40 to
20/50, goes to the OD. The OD ASSUMES that the child has no
interest in keeping his vision clear for life.
Then AUTOMATICALLY, the OD places a "Phoropter" (automated
trial lens kit) in front of his eyes -- and starts with the minus
lens. This minus-lens "increase" in continued until the child
gets SHARPEST VISUAL ACUITY POSSIBLE. This typically turns out to
be -2.0 diopters. (This is a vast over-prescription for a child
with 20/40 to 20/50 vision.)
There is NO DISCUSSION about being "careful" with that -2.0
diopter lens, to avoid ANY USE except for "black-board". That is
the official "accepted" policy of dealing with the general public.
No discussion, no review, no choice. Where is the
"professionalism" of these people? But, now let us "add" the plus
lens to this "mix".
Chances are the OD does not "like" plus-prevention -- because
even that SUGGESTION raises serious doubts about prescribing "Best
Visual Acuity" for a child.
WHEN AVOIDING THE MINUS LENS WOULD BE THE BEST FIRST STEP.
With this un-questioned "policy" in place, and a "blind
study", then NO ONE WILL LEARN ANYTHING.
YOU CAN'T DO THIS AND HAVE A PLUS-PREVENTION SCIENTIFIC
STUDY.
That becomes the FIRST ISSUE YOU DISCUSS WITH
ENGINEERING/SCIENTIFIC STUDENTS.
But I am asked to "prove" that plus-prevention works --
before I am "allowed" to conduct plus-prevention. That is a
PERFECT, "Catch-22" -- and will block any and all true preventive
efforts. Let us be reasonable about this issue.
But given this terrible blindness, I can provide an analysis
for MOTIVATED students, to show that the results can (or will)
exceed the "highly significant" level (in science and statistics).
This would REQUIRE a person who has, or will obtain and
ENGINEERING degree, who understand the meaning of "standard
deviation" and how to apply the concept to his own study.
Further, it would require that the engineer READ his Snellen,
and measure his refractive STATE(Snell). This is not work for a
child. I would need about 60 students (would-be pilots) who would
not be intimidated by their own study. (I assume 10 will drop out
during the study).
We know that the "plus" has the desired effect, and, using
the Oakley-Young data, can project a developing difference of
about 1/2 diopter between the test and control groups. I am
wearing a "plus" for ALL CLOSE WORK. If I can do it -- then THEY
CAN DO IT.
After the introductions, 30 would be wearing a +2.5 diopter
for all close work -- at home, at school. This would make what
they are doing very obvious to the entire school.
This would be continued for six to nine months. The control
group would not wear a plus, but would do the same measurements as
the plus group. There would be "positive" medical over-sight, but
not "control". Given what I know about pilots, I think they would
do it.
The study would be restricted to students no worse that
20/70, and no "deeper" than -1.5 diopters.
Assuming you could organize this type of study (seems to be
impossible), here are the PROJECTED RESULTS:
The equation:
Were N = Number of eyes.
Xc - Xt
Z = ______________________________________________________________
Square Root of [ ( Sigma-c ^ 2 / Nc) + ( Sigma-t ^ 2 / Nt ) ]
Using very REASONABLE VALUES: Control Group, Down -1/4
diopter Plus Group, Up +1/4 diopter.
- 1/4 - (1/4)
Z = ______________________________________________________________
Square root of [ ( 0.35 ^ 2 / 50) + ( 0.35 ^ 2 / 50 ) ]
-1/2 Diopters
Z = _________________
0.070 Diopters
Z = 7.14
C = The control group
T = The test (or plus) group.
Sigma-c = The Standard-Deviation of the control group
Sigma-t = The Standard-Deviation of the test (plus) group.
Xc = The average of the control group.
Xt = The average of the test (plus) group
========================
In statistics, a level of 0.05 is called a significant
result.
A level of 0.01 is called HIGHLY SIGNIFICANT.
This test, values of greater-than 2.33 are HIGHLY SIGNIFICAT.
If you achieve this result -- the study should be continued.
If you don't then the study would be wrapped up.
But the point is this.
A difference of 1/2 diopter in nine months is a HIGHLY
SIGNIFICANT RESULT.
But it would be up to each man to judge this at the end of
the nine months.
In fact I think the results would eventually far exceed these
preliminary results, with a large number initially at -1.5
diopters, clearing their Snellen to better-than 20/40, and
eventually to 20/20.
But further, if continued, their refractive STATE(Snell)
would move positive (necessary for 20/20).
But I can only "project" the Oakley-Young results -- as a
calculation of what is possible.
http://www.geocities.com/otisbrown17268/bifig1.gif
But since this proposed study will be BLOCKED by the
powers-that-be, it follows that it must be the person's own wisdom
to understand WHY he must do prevention himself.
But if the issue is SCIENCE, then this study would succeed
WITH THE RIGHT PEOPLE.
======================
Subject: The expected REASONABLE Standard-Deviation for
Refractive STATES(Snell)
Re: Measurements to always be made by engineers and pilots.
Re: There own enlightened self-interest should "power" the
study.
This study would involve educated pilots-students, entering a
four year college, with visual acuity of no worse than 20/70, and
refractive STATES no worse than -1.5 diopters.
Here is the calculation of "Sigma" for a population of eyes
on the threshold of nearsightedness -- who, have a REASONABLE
expectation to clear their Snellens back to normal, and move their
refractive STATE from a negative to a positive value.
With the restriction of pilot-students with refractive STATES
of from zero to -1.5 diopters, and visual acuities from 20/30 to
20/70, here are the expected values they would obtain from their
individual eyes.
These would be how the typical values would be recorded by
the students.
Refractive State and Number of eyes.
Ref-State -- Number of Eyes
-0.25 D 3
-0.50 D 14
-0.75 D 16
-1.00 D 25
-1.25 D 24
-1.50 D 18
=============
Total Eyes = 100
Standard Deviation = Sigma = 0.35 diopters.
Average = -1.02 diopters.