Hi,
> Could anybody please let me know the answers? Your help is greatly appreciated. Thank you.
>
> 1. It seems to me that in FSL, the cutoff frequency is in period [s] rather than in Hz. Am I right?
Yes.
> 2. On page 3, what does Mean [1 1] really mean? In the powerpoint, it states "Mean activation". What is that?
It is the mean (average) activation across the two different conditions (each condition being associated with one EV).
> 3. After naming the five contrasts to set up the F-test, what would have happened if we had selected contrasts 3 and 4 in the F-test?
I'm not sure what you are referring to here.
> 4. In the design matrix, time goes down with every 10TRs ticked off on the left. The red bar shows the width of the highpass filter. Each TR is 4.2 sec and the red bar occupies 2.5TRs. So, the cutoff is 2.5*4.2s = 10.5s but the cutoff for high pass filter is set to 100s. I am confused. Could you please clarify?
10 TRs = 10 * 4.2 seconds = 42 seconds. Therefore 2.5 red ticks = 2.5 * 42 = 105 seconds (which would be well within your measurement error of estimating the size as 2.5 ticks).
> 5. According to the practical, after I have pressed "Estimate high pass filter" and returned to the Data-tab, I was supposed to see the value changed to 90 seconds. However, FSL returned 1908. I have repeated the steps several times but still got the same inconsistency. Could you please let me know what went wrong?
You may have an older version of FSL, as this has changed. For very short designs (like used in the practical) it could be extremely conservative. In normal length designs it should be fine.
All the best,
Mark
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