关于confidence limit 的求助？

cboboc

在haung的《A confidence limit for the empirical mode
decomposition and Hilbert spectral analysis》中提到，因为采取的s只不同，有可能出现各次的imfs个数不同，所以可采用将希尔伯特谱进行平均，这样就能在预分配的时间和频率空间上就有着同样数量的bins，简单说：就是采用加上或者减去68%置信水平的标准差，或者减去或者加上95%置信水平的两个标准差。原文是：Under such conditions, it is possible to implement the averaging to the Hilbert spectra, which can have the same number of bins in frequency and temporal space pre-assigned. For simplicity, plus and minus onestandard deviation for the 68% confidence level has been adopted (or plus and minus
two standard deviations for the 95% confidence level)
请问各位大侠，bins该怎么理解呢？还有“加上或者减去68%置信水平的标准差”和“减去或者加上95%置信水平的两个标准差”怎么理解呢 ？