The Wear Time Validation (WTV) tool in ActiLife allows users to easily flag invalid data (or, data collected when a device was not worn) for exclusion from further analysis. WTV also provides a summary of the wear-time and non-wear time results from the datasets. The Data Screening Criteria allow users to define non-wear periods. Data flagged as non-wear is not removed from the *.agd file - it is simply flagged as "wear time" or "non-wear time".
Define a non-wear period
This section provides options for defining the non-wear period. ActiLife will use this information to scan the data for non-wear bouts.
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Begin non-wear bout after ____ minutes/epochs of consecutive zeros - After scanning the data and detecting the selected number of consecutive zeros, ActiLife will begin flagging data as "non-wear time". The leading zeros detected during this process will be flagged retroactively (after they have been initially scanned). Data will be flagged as "non-wear time" until the Spike Tolerance is exceeded.
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Use Vector Magnitude - When checked, ActiLife scans the vector magnitude of three-axis data (when available) to detect wear or non-wear time. When unchecked, ActiLife scans only Axis 1 (the vertical axis - see users' manual for details) to detect wear/non-wear times.
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Use an activity threshold of _____ counts per minute/epoch - Instead of looking for zeros to qualify non-wear time, this option allows the user to set a non-zero activity threshold requirement for wear-time. Data below this value will be qualified as "zero".
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Spike Tolerance ____ minutes/epochs - This option allows the user to set a "spurious count" option as described in ______. ActiLife will continue scoring a non-wear bout as non-wear until it detects more than the Spike Tolerance number of epochs above zero (or above the activity threshold, if that option is enabled).
Optional Screening Parameters
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Ignore wear periods less than _____ minutes/epochs - Because of the WTV algorithms used, some wear periods may be very short (shorter than the spike tolerance). Use this option to set the minimum length of an acceptable wear period.
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Flag entire day as invalid if wear time less than _____ minutes/epochs - Use this setting to flag an entire 24 hour day as invalid if there are less than the selected amount of valid (wear-time) minutes or epochs in the day.