Compact and average

  •   COMPACT & AVERAGE...      Makes a compact version of the data by breaking it into a series of blocks of user-specified length, and then computing a mean and S.D. for each of the blocks.  Each block contains a fixed number of cases, and the block duration (in time units) depends on this number and the sample interval.

  • Compacted data can be saved as tab-delineated text files containing both means and standard deviations.  It is also shown on-screen in the regular plot area.  This can make it easier to see trends in noisy data, and is also useful for preparing data for publication -- a figure broken into a series of means and S.D.s is frequently easier to read than a simple line plot (particularly if the raw data are somewhat noisy).

    NOTE:  although the plot area on the screen shows the compacted version, any analyses are performed on the original data, which is shown as normal in the block window.

    This example shows a 20-fold compaction, which equates to a 'block size' of 30 seconds for each mean and S.D. computation.  The 'highlight data means' and 'show S.D.' options are selected; this will show the mean values as a dot, and the SDs as vertical lines in the plot area (in active screen mode only if there are more than screenwidth cases).

    Some operations, like Baseline with user-selected points, are difficult to use if the data are shown in compacted form (although you can still read the uncompacted values for the cursor position in the data bar).  It's probably best to shift to the regular display ('normal plot') for these operations.


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