sta

Statistical Analysis (Application).

Application sta is to perform a statistical analysis of the light curve of 1 series of data. It is run in the Question/Answer user interface by typing:

[n]Xronos> sta

[n]Xronos> sta [series1]

[n]Xronos> sta[/qualifier1/qual2/... etc]  [series1]

More on sta

The default newbin time is either the maximum bin time (if fewer than 512 newbins are expected) or such as to give a single interval with 512 newbins at most. The number of newbins per interval determines the length of the time axis of each interval and therefore the number of intervals that will be produced. Note that in light curve applications each frame can contain only results from one interval (i.e. intervals and frames coincide; see also chapter 2 terminology). No output file is produced by sta. The results are output to the screen. A number of quantities are calculated:

• Newbin integration time (x2 gives the shortest timescale sampled in the analysis)
• Interval duration (gives the longest timescale sampled)
• Number of good (accepted) newbins in interval
• Average (and its error)
• Standard deviation
• Minimum and maximum count rates in interval
• Variance (and its Gaussian error), as evaluated from the data scatter
• Expected variance from a constant source (and its Gaussian error), as evaluated from the errors in the newbin count rates (corrected for dead time effects as appropriate)
• Third moment
• Average absolute deviation
• Skewness (and its Gaussian error)
• Kurtosis (and its Gaussian error)
• RMS fractional variation (and its Gaussian error) or a 3 sigma upper limit if the variance is not larger than the expected variance at a confidence level higher than 99.86%
• Chi-square and corresponding number of degrees of freedom
• Constant source probability associated to the Chi-square value
• Constant source probability from a Kolmogorov-Smirnov test (note however that, strictly speaking, this test should be applied only to unbinned data; moreover this test often fails if used with background subtracted light curves of faint sources)