## 7.4 RQA of circle-tracing data

• Analyse the circle tracing data we recorded during the lecture.
• Study what happens to the RQA measures if you shuffle the temporal order (see e.g. the solution to th HRV assignments).
• Package fractal contains a function surrogate. This will create so-called constrained realisations of the time series. Look at the help pages of the function, or study the Surrogates Manual of the TISEAN software and create two surrogate series, one based on phase and one on aaft.
• Look at the RQA measures and think about which $$H_0$$ should probably be rejected.
• If you want to be more certain, you’ll have to create a test (more surrogates). The TISEAN manual provides all the info you need to construct such a test:

“For a minimal significance requirement of 95% , we thus need at least 19 or 39 surrogate time series for one- and two-sided tests, respectively. The conditions for rank based tests with more samples can be easily worked out. Using more surrogates can increase the discrimination power.”