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statistics (was COLD FUSION)

On Monday, Oct 18, 2004, at 07:57 America/New_York, Brian Whatcott
wrote:

I would prefer to see the usual tests for significance - (at what
level?)
rather than what appears to be an opinion as to significance.

Brian W

At 09:23 PM 10/17/2004, Ludwik, you wrote:
//
I was counting tracks on CR-39
exposed to a Ti foil sent to me by S. Jones last summer.
The result was 225 tracks (on two square inches of
CR-39) for the surfaces exposed to the foil (for 55 days)
and 132 for control surfaces that were not exposed.
Working with a Geiger counter I would say that the
difference is very significant.
//
Ludwik Kowalski

//
It is doubly important for a person researching in cold fusion
effects
to demonstrate the usual experimental protocols.


Instead of performing a test of significance myself I will share row
data. With the microscope magnification = 40 I examined 50 fields on
the foreground (two CR-25 surfaces exposed to Ti) and 50 fields in the
background (two surfaces that were not exposed). This produced two
sets of numbers shown below. Numbers are tracks per field. I wish I had
time to perform the analysis by myself; please let me know what is the
probability that the net difference between the foreground (225 tracks)
and the background (132) is coincidental. I predict that the answer
will be around 0.005 or less. Please share your finding; I will mention
them in my presentation. But I am leaving this Wednesday afternoon.
Your help will be appreciated.

Foreground:
8, 4, 2, 8, 2, 6, 7, 5, 7, 6, 4, 5, 9, 4, 4, 4, 6, 3, 2, 0, 3, 4, 4, 2,
3, 3, 3, 3, 3, 8, 5, 1, 4, 5, 4, 3, 6, 6, 4, 6, 6, 7, 3, 10, 7, 1, 1,
8, 3, 3

Background:
5, 0, 2, 1, 1, 4, 3, 4, 2, 3, 4, 3, 2, 4, 2, 4, 2, 3, 4, 2, 0, 5, 1, 2,
2, 2, 5, 2, 2, 4, 2, 2, 3, 1, 1, 2, 1, 3, 7, 2, 1, 5, 1, 3, 3, 3, 2, 3,
3, 4

I hate situations in which one has to rely on statistics. But such
situations a frequent, even in physical sciences.
Ludwik Kowalski