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SC-IAT Scoring
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becgwin
becgwin
posted 10 Years Ago
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Hi,
I ran an SC-IAT last year based on the Inquisit task library version dated 03-26-2013 and I am slightly confused by the summary output. While I get no expressions.da (it appears to leave out calculations of the practice trials), I do get an expressions.db (which according to previous posts is for the test trials - topics3444) and an expressions.d (which according to same post is meant to combine practice and test trials). The expressions.d seems to be the expressions.da divided by 2. The expressions.latdiffb and expressions.latdiff are identical which I think makes sense if the practice trials are not included. I have since seen the updated version of the SC-IAT (dated 11-21-2013) and the programmed output makes more sense to me, so I assume it may have been amended in part to address this issue. I just want to confirm that expressions.db in my summary output is D for test trials, and what I should use assuming I am satisfied to exclude trials larger than 10000ms and error trials. Also, can anyone explain what expressions.d is in this case when it appears the practice trials were not included in the analysis, and yet it differs from expressionsdb. The script is as follows:
* 1 is compatible, 2 is incompatible
* a is first block, b is second block
<expressions>
/ m1a = values.sum1a / values.n1a
/ m2a = values.sum2a / values.n2a
/ m1b = values.sum1b / values.n1b
/ m2b = values.sum2b / values.n2b
/ sd1a = sqrt((values.ss1a - (values.n1a * (expressions.m1a * expressions.m1a))) / (values.n1a - 1))
/ sd2a = sqrt((values.ss2a - (values.n2a * (expressions.m2a * expressions.m2a))) / (values.n2a - 1))
/ sd1b = sqrt((values.ss1b - (values.n1b * (expressions.m1b * expressions.m1b))) / (values.n1b - 1))
/ sd2b = sqrt((values.ss2b - (values.n2b * (expressions.m2b * expressions.m2b))) / (values.n2b - 1))
/ sda = sqrt((((values.n1a - 1) * (expressions.sd1a * expressions.sd1a) + (values.n2a - 1) * (expressions.sd2a * expressions.sd2a)) + ((values.n1a + values.n2a) * ((expressions.m1a - expressions.m2a) * (expressions.m1a - expressions.m2a)) / 4) ) / (values.n1a + values.n2a - 1) )
/ sdb = sqrt((((values.n1b - 1) * (expressions.sd1b * expressions.sd1b) + (values.n2b - 1) * (expressions.sd2b * expressions.sd2b)) + ((values.n1b + values.n2b) * ((expressions.m1b - expressions.m2b) * (expressions.m1b - expressions.m2b)) / 4) ) / (values.n1b + values.n2b - 1) )
/ da = (m2a - m1a) / expressions.sda
/ db = (m2b - m1b) / expressions.sdb
/ d = (expressions.da + expressions.db) / 2
/ latdiffa = m2a - m1a
/ latdiffb = m2b - m1b
/ latdiff = ((values.sum2a + values.sum2b) / (values.n2a + values.n2b)) - ((values.sum1a + values.sum1b) / (values.n1a + values.n1b))
/ attitude = "unknown"
</expressions>
Finally, can any-one confirm that the raw error trial latencies are uncorrected, or corrected for in calculations only by their exclusion? That way I can easily run my own analysis if I want to change the parameters e.g. delete trails less than 350ms etc.
Thanks,
Rebecca
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becgwin
-
10 Years Ago
expressions.da, expressions.db and expressions.d represent what...
Dave
-
10 Years Ago
Hi Dave, Hi Dave, That helps a lot. Thanks again for answering my...
becgwin
-
10 Years Ago
> It doesn't however include any incorrect response latencies in...
Dave
-
10 Years Ago
Thanks for confirming that Dave. I'll move on now with more...
becgwin
-
10 Years Ago
Hello, Does anyone have SPSS syntax for scoringthe SC-IAT? I am...
AC
-
9 Years Ago
If you are going to use any existing syntax as the basis, you should...
Dave
-
9 Years Ago
Hello, thank you so much for the speedy for the response. I cansee the...
AC
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9 Years Ago
> Even if Ididn’t need to recalculate I can’t get my head around...
Dave
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9 Years Ago
Hi again, for what I think its the final time. Surprisingly I seem to...
AC
-
9 Years Ago
Hi Dave, sadly I am back with another question. My D scores were...
AC
-
9 Years Ago
Yes, that is correct. The differences in the scoring are also...
Dave
-
9 Years Ago
Hi Dave, I did read the info in the script beforerunning the...
AC
-
9 Years Ago
Hi again, I thought I would paste in the section of the SC-IAT script...
AC
-
9 Years Ago
*All trials* with latency <= 10000 are counted towards values.n1...
Dave
-
9 Years Ago
Thank you Dave, I am sorry I over lookedon trial end. I must confess...
AC
-
9 Years Ago
The script does not calculate two D-scores. There is a single one,...
Dave
-
9 Years Ago
Regarding Greenwald et al. (2003), p. 210: It depends on what...
Dave
-
9 Years Ago
No, I didn’t think it would make sense, butas I am not a great stats...
AC
-
9 Years Ago
Hi Dave, You may have realised, but the reason I was getting two D...
AC
-
9 Years Ago
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