Some readers of this newsgroup may remember a message i posted some weeks back about analysing the data from some pilot tests concerning dialling methods from a mobile phone (see: what test do i run?? help for a novice please).
Well i have now done the main body of my research, and unsurprisingly i am in somewhat of a muddle with my stats again. I do have tutors who are SUPPOSED to help me, but they have made themselves both unavailable and unintelligible. The details are below. May i first though, thank profusely anyone who is taking the time to read this and offer help. I cant express how much i greatly appreciate and am utterly surprised by the amount of people who are willing to offer help to complete strangers. Anyway, that out of the way, heres the details (pared down as much as possible)..... I did a direct comparison of two methods of dialling a name from a mobile phone 'look-free'. The first was voice activated dialling which im sure most of you are familiar with. The second was a new method using text-to-speech technology (TTS): Users press a button to start. The system then 'reads' the first name in the users list. The user then scrolls through the names in their list, whilst the system reads each one out. When the desired name is reached, the user presses the dial button. I was interested to know: A) Which was faster on successful dials B) Which had a higher error rate (either failed dial attempts or wrong names dialled) C) Which was faster OVERALL, once the errors had been included D) Which ones performance was more affected detrimentally by background noise 12 subjects took part. Each subject had their own 10 name phonebook. Each subject had to dial every name in their phonebook (randomly presented) under four different conditions (also randomised): 1) Voice dialling (VD) + quiet 2) VD + noise 3) TTS dialling + quiet 4) TTS dialling + noise On the data i collected i did the following (all t tests): 1) speed of successful dials, VD vs TTS, with quiet 2) speed of succesful dials, VD vs TTS, with noise etc... for aspects A, B, C listed above. For D (effect of background noise) i did: 1) Speed of succesful dials, TTS in quiet vs TTS in noise 2) Speed of succesful dials, VD in quiet vs VD in noise etc... for error rates and speed of dialling including errors Phew! that was a lot of info... My question im afraid is somewhat vague due to the fact that my tutors have confused me. Below is the source of my confusion: My tutors say that i cant produce these t tests without first running a 2 way repeated measures ANOVA on all the data together to see if there is a general effect first, only then can i parcel the analyses into those for quiet and those for noisy. To quote them: "Start the analyses with 2-way ANOVAs of the overall data from each quiet/noisy/VAD/TST set and then go on to do the separate t-tests" I just cant get my head round this. I guess my main problem is that i dont know what an ANOVA does, and consequently when i do them i really have no idea what the output means. To me it just makes no sense to analyse the data with the noisy and quiet conditions taken together - it is not interesting to know if there is an effect between VD Quiet and TST noisy for example, because it is not a fair comparison. So what do these tests actually tell me? Are my tutors misunderstanding the point of my experiements? I know this is vague, but because of my confusion im not really sure of the exact question myself. Can anyone help? thanks again, and sorry if i have wasted anyones time with a non-answerable question DN . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
