"Pingu" <[EMAIL PROTECTED]> schreef in bericht news:[EMAIL PROTECTED] > Ok.....sort of... > > Im still not fully clear, but rest assured you have already done a far > superior job to my tutors. > > Lets say that VD dialling and TST dialling in quiet conditions both > show a very similar performance in terms of dialling speed. When noise > is introduced, however, VD becomes much slower than TST because the > voice recogniser has a lot of interference to deal with. > > My 2 t-tests would show a non-significant difference between the > systems in quiet conditions and a significant difference between them > in noisy conditions. > > What will the ANOVA show? So far i just cant see how the results from > an ANOVA can describe such a clear distinction as this.
The analysis of your data should start with 12x4 tables of means per subject for each of your 4 treatment combinations (dialing methods x noise conditions). It is perfectly valid to compare any two treatment combinations using a t-test for paired data, or equivalently, using a t-test on the differences, calculated per subject. What ANOVA (with 3 factors: dialing methods, noise level and subject as a blocking factor) may add is a more efficient estimate of error variance, if this variance is believed to be the same for all treatments (which appears to be doubtfull in your case). > > p.s - It would really help me if you framed your anwer in terms of the > output i will get from SPSS. When i ran the ANOVA i did 2 factors > (noise/quiet) with two levels (TST/VD). The output gives three > figures: > > Noise = X > Quiet = X > Noise*Quiet = X > This is nonsense. Your factors are dialing methods and noise level, each with two levels (plus the above mentioned blocking factor subjects!). . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
