#### RobertL

##### Newbie level 5

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I'm new here and I'm also fairly new to Matlab. I have to analyse some data that I've retrieved during experiments for my Master's thesis.

Picture: raw data

file.php (561×420) | Awesome Screenshot

The data I'm talking about here is the moment in time (on the x-axis) versus speed (y-axis). Because of the instruments I use to measure, the data is somewhat unprecise so I need some filtering. It's no problem for me to write something to take several points to determine an average value (see figure below, taken over 10 points) but this figure is still not what I need to take conclusions. (And I think it's even better to filter with a high or lowpass filter, but I don't (yet) know how to do this in Matlab).

file.php (561×420) | Awesome Screenshot

I allready thought of some ways to analyse my data:

- One hypothesis of mine is: if participants are better in the grasping task, they need less 'bumps' to reach the target in my experiment (they already reach it in one arm movement). So, I have to do something like a regression analysis on the filtered data. That's something like: "Do I need a cubic, quartic, quintic, sextic, septic or octic polynomial to describe the outcome best? When isn't the polynomial's fit improving significantly anymore?"

Can Matlab determine what order polynomial is the best, preferably automatic? I allready found the polytool or some basic fitting tools after plotting, but it doesn't tell me how good the fit is and it's many data to analyse it by hand.

- Also, if a participant is better (experts) they have less bumps, that are smaller (higher) because the reach movement is fast. Novices instead need to controll their movements more and have 'bumps' that are wider. Maybe there's something to analyse the shape of the first bump automatically in Matlab?

- Another thing I need is a spectrum derivated from my data.

Do some Fourier analysis (I think this should be possible on the unfiltered data) to determine what frequencies (speeds) are relevant in the data. This way, I can connect frequencies to known data about body constants (e.g. arm muscle time constants, speeds etc). Besides that I approximately know what Fourier analysis is, I don't know how to implement it. I allready found something about the fft-function, but that gives me complex numbers and I think I don't need them..

I know that there are many and maybe stupid questions, but I hope someone can and is willing to help me.

Thanks in advance!

Robert

I'm sorry if my English is not perfect.