Find whether there is a trend over time or the data is completely random

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Hello! I am working with ECG signals and I have extracted several features of the QRS complexes. My wish now is to find whether those features change in a certain way over time or the change is totally random. Which would a good approch to do this ?

回答(2 个)

Image Analyst
Image Analyst 2020-8-10
Star Strider will know, but until he answers the only thing I can suggest is looking into the chi-squared test.

John D'Errico
John D'Errico 2020-8-10
This really is not a MATLAB question, as you have no idea how to compute what you want, and your question is too vague to have a true answer.
There are many ways to see if data has a trend over time. For example, you might do a simple linear regression fit, thus y as a function of time. Test to see if the slope is significantly different from zero. If the slope is bound away from zero, then you have an answer.
Or you might simply choose to do a split the data into two segments or blocks, as a function of time. Now do a test, comparing the mean of block1 to the mean of block2. Are they statistically different? You might use tests like an anova, or a non-parametric test. Lots of them in the stats toolbox, and I am not a statistician to say whch is best, even if I did play at it in a past lifetime.
  3 个评论
John D'Errico
John D'Errico 2020-8-11
Yes. You need to compute it in MATLAB, which has many statistical tests. Sp spend some time researching which statistical test might be appropriate for your problem. Again, there will be multiple tests someone could think of. If linear regression is not apprpriate, then you need to show some examples. Explain why an obvious test is NOT appropriate. But better still is to ask this on a forum where you will find a larger statistical community. Decide how to solve the problem, and only then need you worry about MATLAB code.
Only when you know what to do should you worry about the code to compute it.
Image Analyst
Image Analyst 2020-8-11
Ray, please show a screen shot of your data plotted so we can see the trendline. Maybe you just want to do "baseline correction" like they do in spectroscopy. Attach your data if you want people to try things with it.

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