--- title: Missing Data in the NN Interval description: The first thing to know is that the NN interval data are filtered data. In fact, the calculation of the NN interval is based on the RR interval --- [Skip to content](https://support.hexoskin.com/missing-data-in-the-nn-interval#main-content) - [English](https://support.hexoskin.com/missing-data-in-the-nn-interval) - [Français](https://support.hexoskin.com/fr/données-manquantes-dans-les-intervalles-nn) English Show submenu for translations [More support](https://support.hexoskin.com/kb-tickets/new?hsLang=en) [![Hubspot - Hexoskin Logo - Rectangle](https://support.hexoskin.com/hubfs/Hubspot%20-%20Hexoskin%20Logo%20-%20Rectangle.svg)](https://support.hexoskin.com/?hsLang=en) Open main navigation Close main navigation - - [English](https://support.hexoskin.com/missing-data-in-the-nn-interval) - [Français](https://support.hexoskin.com/fr/données-manquantes-dans-les-intervalles-nn) English Show submenu for translations - [More support](https://support.hexoskin.com/kb-tickets/new) - [Contact us](https://support.hexoskin.com/kb-tickets/new) [Contact us](https://support.hexoskin.com/kb-tickets/new?hsLang=en) How can we help you? - There are no suggestions because the search field is empty. 1. [Hexoskin Support Community](https://support.hexoskin.com/?hsLang=en) 2. [Hexoskin Data Analysis](https://support.hexoskin.com/hexoskin-data-analysis?hsLang=en) # Missing Data in the NN Interval The first thing to know is that the NN interval data are filtered data. In fact, the calculation of the NN interval is based on the RR interval (for more details, please refer to [API documentation](https://api.hexoskin.com/docs/resource/datatype/)). Therefore, it is possible that there is a gap in the data because unreliable RR intervals were excluded from the calculation. If you want to detect all the QRS complexes without filtering, you might want to use the RR interval data instead of the NN intervals. Please note that to capture consistent data (i.e. avoid unreliable RR intervals), the Shirt needs to fit properly on each participant (for more information, refer to this [link](https://support.hexoskin.com/determining-hexoskin-shirt-size?hsLang=en)) and you need to make sure that all the sensors are in contact with the skin. To obtain a better signal, it is very important to [apply conductive gel (or simply glycerin-based cream)](https://support.hexoskin.com/applying-conductive-cream-on-the-cardiac-sensors?hsLang=en). 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