http://spssx-discussion.165.s1.nabble.com/Longitudinal-comparison-partial-vs-whole-sample-tp5718123p5718400.html
Maybe the OP could provide more information.
Or - what I still assume - maybe there is a good experimental history of
using eye-track data, and a popular experimental paradigm that uses
some standard measures, and there is no reason to tamper with success.
Or, if you were to set out to re-examine the basis of using eye-tracking
data, it might be proper to design a new study that would include
elements of *all* the experimental designs that have been based on
the same conventional measures.
I regarded this data-problem like I have regarded EEG data. That data
was given to me as a number for each of several frequency bands, all
based on thousands of points for every set of 5 numbers; repeated for
multiple scalp reference-points. - There were distributional oddities here,
and I referred to my PI and the literature before dividing through to
get "relative power" and then taking the logits. - As is usually the case,
the simplest single summary was effectively an average, the average
frequency.
IIRC, the same PI also gave me eye-tracking data ... which had decent
distributions, and which I don't remember ever worrying twice about,
and I've buried any recollection of what it consisted of. But it would be
a major project, I suspect, to introduce a variation of the scoring.
To me, it seems a bit out of order for a statistician to intrude on the basic
measures, if there hasn't been a question raised about them, either
directly by the PI or indirectly by weird data distributions.
--
Rich Ulrich
> Date: Tue, 5 Mar 2013 13:54:30 -0800
> From:
[hidden email]> Subject: Re: Longitudinal comparison partial vs. whole sample
> To:
[hidden email]>
> At the end of the day, the OP needs to provide more information about the
> thousands of data points per subject per time point. Given that it is
> eye-movement data, I doubt they're all measures of the same thing--so no
> simple aggregation such as computing a mean. I suspect that 2-dimensional
> eye position is recorded at some fairly high frequency (hence the thousands
> of data points), and then other measures are derived from the raw data
> (involving massive data reduction) -- e.g., direction and latency of an eye
> movement away from fixation in response to some stimulus. It also would not
> surprise me if the situation is more complicated than can be sorted out with
> the exchange of a few e-mails.
>
> HTH.
> ...