Negative RT Data in E-Prime 1.2

[KC]

Thank you for your help Michiel. Our data system involves automatized
data filtration such that outliers are highlighted and those
highlighted values must be manually changed to either the upper or
lower cap (i.e.: average +/- 2*standard error). I was able to contact
the student who created these files and learned that, to correct the
outliers, she had simply "input whichever cap removed the highlighting
from the cell." So, the negative RTs were the result of an error in
data cleaning and not our programming in E-Prime. Thank you for your
advice, it really added to my understanding of E-Prime and will be
very helpful in the case that I come across negative RTs again.

Thanks,

KC

On May 31, 4:35 am, "Michiel Sovijarvi-Spape" <msp... at cognitology.eu>
wrote:
> Hi KC and list,
> I am not aware of a known bug in E-Prime, especially mighty stable 1.2, that
> could cause this. A general, "internal error" seems unlikely to answer the
> question, so the way to go about it would be to A) replicate the error, and
> B) find out what is responsible for the observation - what part of the bug.
> In general then, the task would be to find out how the observed variable is
> related to actual performance, and either shift them or, as you say, filter
> them.
> Scenario one: there's something going on due to incorrect usage of preload.
> Scenario two: there's incorrect calculation of your reading time. For
> instance:
> An instruction screen is shown, the "reading screen" is shown, which has
> 60000 ms maximum, but a response terminates screen ("after you're done
> reading, press space bar"). Reading time is calculated as "ReadingTime =
> ReadingScreen.RTTime - InstructionScreen.OffsetTime". Now, that would
> normally work, but imagine a person is a very slow reader (a minute passes):
> RTTime is never changed to 0, ergo, 0-8062316=-8062316.
>
> Anyway, my point really is, add some debugging (debug.print) to find out the
> exact relationship between your variable coding and what is going on. Then,
> make a decision if you can really be sure you can just filter negative
> times.
> Cheers,
> Michiel
>
>
>
>
>
>
>
> -----Original Message-----
> From: e-prime at googlegroups.com [mailto:e-prime at googlegroups.com] On Behalf
>
> Of KC
> Sent: 30 May 2012 16:43
> To: E-Prime
> Subject: Negative RT Data in E-Prime 1.2
>
> I feel I should preface this message by saying that I am not an E- Prime
> expert. I've recently begun working on some data generated in an experiment
> run using E-Prime 1.2. The data was part of an experiment run by another
> student who has since left our lab. I'm cleaning (filtering outliers) the
> raw Reading Time data right now and I'm seeing a lot of negative values. Why
> is this? Some forums have suggested that it is an internal error of the
> program and that the solution is to update to a more recent version of
> E-Prime, however, I cannot re-run the experiment. In terms of analysis, how
> are these values normally dealt with? Any ideas?
>
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