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. 2011 Jun 24;5:97. doi: 10.1186/1752-0509-5-97

Table 2.

BSA and FFT results from simulated harmonic data with noise and background trends

No. ω ea (%) ep (%) b Inline graphic σFFT Inline graphic σBSA Inline graphic σBSA-NS s-n
1 0.5 1 - - 0.49 0.06 0.5 0 0.5 0.0002 70
2 0.5 10 - - 0.49 0.20 0.5 0.0002 0.5 0.0004 6.5
3 0.5 40 - - 0.49 0.54 0.5 0.0005 0.5 0.0011 1.9
4 0.5 10 10 - 0.49 0.27 0.5 0 0.5 0.0003 4.2
5 0.5 10 40 - 0.49 0.57 0.5 0.0002 0.5 0.0007 2.2
6 0.5 100 40 - 0.49 0.89 0.5 0.0006 0.5 0.0020 0.7
7 0.3, 0.5 10 10 - 0.29, 0.51 0.14 0.3, 0.5 0.0003 0.34 0.0832 1
8 0.5 10 - -t 0 0.15 0.5 0.0002 0.5 0.0002 110
9 0.5 10 - -t2 0 0.19 0.5 0.0002 0.5 0.0002 90
10 0.5 10 - -t3 0.02 0.24 0.5 0.0003 0.5 0.0002 35

Each time series was generated with a sine function of angular frequency, ω, of 0.5 rad/s with a level of noise in amplitude, ea, and phase, ep. In some time series a background trend (b) was included, and in case number 7 an additional sine function of 0.3 rad/s is present. The resulting function was sampled 200 times at an interval of 1 s. Results from FFT are presented in the form of the angular frequency with the highest power, Inline graphic, and the estimated standard deviation, σFFT. The Bayesian frequency estimate at the maximum posterior point is denoted by Inline graphic and its standard deviation by σBSA. For comparison, the expectation value of ω and its standard deviation computed using BSA and Nested Sampling (BSA-NS) are denoted by Inline graphic and σBSA-NS. Values of σ below 10-8 are listed as 0. The estimated signal-to-noise ratio (s-n) from the Bayesian analysis is given in the last column. The BSA and BSA-NS approaches deliver the same results, apart from the case of multiple frequencies in a 1D search of ω (case No. 7), which for BSA-NS leads an intermediate estimate between the frequencies with a higher standard deviation.