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. 2019 Mar 26;7(3):e12171. doi: 10.2196/12171

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©Yuan-Chien Pan, Hsiao-Han Lin, Yu-Chuan Chiu, Sheng-Hsuan Lin, Yu-Hsuan Lin. Originally published in JMIR Mhealth and Uhealth (http://mhealth.jmir.org), 26.03.2019.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in JMIR mhealth and uhealth, is properly cited. The complete bibliographic information, a link to the original publication on http://mhealth.jmir.org/, as well as this copyright and license information must be included.

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Use/nonuse reciprocity parameters. (a) A schematic and the equation used to calculate the root mean square of the successive differences (RMSSD). Ai is the duration of a use or nonuse epoch. There are (n-1) successive differences of use/nonuse episodes. The RMSSD was calculated to be the square root of the mean square. (b) A schematic and the equation used to calculate the Similarity Index (SI), Xi refers to the duration of a nonuse (gray) episode, Yi refers to the duration of a use (black) episode. Each nonuse episode (Xi) corresponds to 3 successive use epochs (Yi, Yi+1, and Yi+2). k is the number of nonuse episodes in a day. Thus, the SI is the average absolute difference between the nonuse and use episodes. (c) A schematic and the equation used to calculate the Control Index (CI), Xi refers to the duration of a nonuse (gray) episode and Yi refers to the duration of a use (black) episode. Each nonuse episode (Xi) corresponds to 3 successive use epochs (Yi, Yi+1, and Yi+2). k is the number of nonuse episodes in a day. Thus, the CI is the average of the absolute differences between 1 nonuse episode and the total of the following 3 use episodes. RMSSD: root mean square of the successive differences.