Ed, no the fact that you don't, can't or won't estimate the precision
doesn't change anything (only as you say it becomes a poorly designed
experiment). A measurement has a standard deviation regardless of whether
you possess an estimate of its value or not. The exact true value of the
standard
Ed, sorry for delay. I was not trying to make any significant distinction
between controllable and potentially controllable: from a statistical
POV they are the same thing. The distinction is purely one of
practicality, i.e. within the current experimental parameters is it
possible to eliminate
Pete,
Actually, I was trying to say the opposite - that the decision to
include something in the model (or not) could change the nature of the
error.
Duly noted
Pete
PS - IIUC := ?
IIUC - If I Understand Correctly
--
Bullseye! Excellent shot, Maurice.
Kay,
the latter is _not_ a systematic error; rather, you are sampling (once!) a
statistical error component.
OK. Other words, what is potentially removable error is always
statistical error, whether it is sampled or not.
So is it fair to say that if there are some factors that I either do
Ian,
thanks - I think I had it backwards after reading your first post and
thought of controllable errors being those that can be brought under
conrtol by sampling, whereas uncontrollable would be those that cannot
be sampled and therefore their amplitude is unknown.
Yet you also seem to agree
The precision must be obtained either from multiple measurements which must
be representative of the measurements you propose to make, or if the
measurement consists of a count (say of photons) then from counting
statistics, or a combination of the two. This must be done by either by
prior
OK. Other words, what is potentially removable error is always
statistical error, whether it is sampled or not.
Clarification - what I meant is potentially removable by proper sampling
and reducing standard error to zero with infinite number of
measurements. Not removable by better
Ian,
On Wed, 2013-03-13 at 19:46 +, Ian Tickle wrote:
So I don't see there's a question of wilfully choosing to ignore. or
not sampling certain factors: if the experiment is properly calibrated
to get the SD estimate you can't ignore it.
So perhaps I can explain better by using the same
On Mar 13, 2013, at 1:36 PM, Ed Pozharski wrote:
But what if I only have one measurement worth of sample?
Is it proper to use statistical analysis for a single measurement? I thought
statistics, by definition, means multiple measurements.
Alex
:05 pm
Subject: Re: [ccp4bb] statistical or systematic? bias or noise?
On Mar 13, 2013, at 1:36 PM, Ed Pozharski wrote:
But what if I only have one measurement worth of sample?
Is it proper to use statistical analysis for a single measurement? I thought
statistics, by definition, means
://journals.iucr.org/d/issues/2007/07/00/bw5202/ ).
Cheers, tom
From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of
mjvdwo...@netscape.net
Sent: Thursday, 14 March 2013 12:07 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] statistical or systematic? bias or noise?
I think
@JISCMAIL.AC.UKmailto:CCP4BB@JISCMAIL.AC.UK
Sent: Wed, Mar 13, 2013 3:05 pm
Subject: Re: [ccp4bb] statistical or systematic? bias or noise?
On Mar 13, 2013, at 1:36 PM, Ed Pozharski wrote:
But what if I only have one measurement worth of sample?
Is it proper to use statistical analysis for a single measurement? I thought
On Mon, 11 Mar 2013 11:46:03 -0400, Ed Pozharski epozh...@umaryland.edu wrote:
...
Notice that I
only prepared one sample, so if on that particular instance I picked up
4.8ul and not 5.0ul, this will translate into systematically
underestimating protein concentration, even though it could have
Salve,
I would like to solicit opinions on a certain question about the
relationship between statistical and systematic error. Please read and
consider the following in its entirety before commenting.
Statistical error (experiment precision) is determined by the degree to
which experimental
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Hash: SHA1
Hi Ed,
only prepared one sample, so if on that particular instance I
picked up 4.8ul and not 5.0ul, this will translate into
systematically
I don't share your opinion about a single measurement translating into
a systematic error. I would call
On 11 March 2013 15:46, Ed Pozharski epozh...@umaryland.edu wrote:
Notice that I
only prepared one sample, so if on that particular instance I picked up
4.8ul and not 5.0ul, this will translate into systematically
underestimating protein concentration, even though it could have equally
Hi Ed,
Ed Pozharski wrote:
An interesting thing happens when I do that. What used to be a
systematic error of pipetting now becomes statistical error, because my
experiment now includes reproducing dilution of the stock. In a
nutshell,
Whether a particular source of error contributes to
Tim,
On Mon, 2013-03-11 at 18:51 +0100, Tim Gruene wrote:
I don't share your opinion about a single measurement translating into
a systematic error. I would call it a poorly designed experiment in
case you were actually iterested in how accurately you determined the
protein concentration.
Ian,
thanks for the quick suggestion.
On Mon, 2013-03-11 at 18:34 +, Ian Tickle wrote:
Personally I tend to avoid the systematic vs random error distinction
and think instead in terms of controllable and uncontrollable errors:
systematic errors are potentially under your control (given a
Pete,
On Mon, 2013-03-11 at 13:42 -0500, Pete Meyer wrote:
My take on it is slightly different - the difference seems to be more
on
how the source of error is modeled (although that may dictate changes
to
the experiment) rather than essentially depending on how the
experiment
was
By the way, am I the only one who gets this thing with every post? If
anyone can ask Jin Kwang (liebe...@korea.ac.kr) to either clean up his
mailbox or unsubscribe, that would be truly appreciated. Delete button
is easy and fun to use, but this has been going on for quite some time.
On Tue,
I've just have the same thing.
I'll write to Jin Kwang and remove him from the bb-list if he will not respond
by tomorrow evening
Andrey
On 11 Mar 2013, at 19:27, Ed Pozharski wrote:
By the way, am I the only one who gets this thing with every post? If
anyone can ask Jin Kwang
It should stop. I'll see after sending this message.
On 11 Mar 2013, at 19:27, Ed Pozharski wrote:
By the way, am I the only one who gets this thing with every post? If
anyone can ask Jin Kwang (liebe...@korea.ac.kr) to either clean up his
mailbox or unsubscribe, that would be truly
Ed,
Ed Pozharski wrote:
IIUC, you are saying that nature of the error should be independent of
my decision to model it or not. Other words, if I can potentially
sample some additional random variable in my experiment, it contributes
to precision whether I do it or not. When it's not
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