A media content viewing estimation system comprising a plurality of operationally connected modules including: a receive module to receive a time measurement of how long at least part of a content item was rendered by an end-user rendering unit and outputted for display to an audio-visual outputting arrangement by the end-user rendering unit during a time window, the time window being one from a configurable set of variable length time windows, wherein the length of the time window is longer for a period correlating to a statistically high confidence level of user presence when compared to a period correlating to a statistically low confidence level of user presence; an activity determination module to determine user interaction with the end-user rendering unit and/or the audio-visual outputting arrangement; an average content item duration module to calculate an average content item duration of a plurality of content items rendered by the end-user rendering unit during the time window; and a viewing estimation module to estimate viewing by the user of the at least part content item such that if user interaction was not determined during the time window then time attributed to the viewing of the at least part content item is set to the minimum of: a capping limit; the time measurement of how long the at least part content item was rendered and outputted for display to the audio-visual outputting arrangement, wherein the capping limit is higher for a period correlating to a statistically high confidence level of user presence when compared to a period correlating to a statistically low confidence level of user presence; and the average content item duration. a receive module to receive a time measurement of how long at least part of a content item was rendered by an end-user rendering unit and outputted for display to an audio-visual outputting arrangement by the end-user rendering unit during a time window, the time window being one from a configurable set of variable length time windows, wherein the length of the time window is longer for a period correlating to a statistically high confidence level of user presence when compared to a period correlating to a statistically low confidence level of user presence; an activity determination module to determine user interaction with the end-user rendering unit and/or the audio-visual outputting arrangement; an average content item duration module to calculate an average content item duration of a plurality of content items rendered by the end-user rendering unit during the time window; and a viewing estimation module to estimate viewing by the user of the at least part content item such that if user interaction was not determined during the time window then time attributed to the viewing of the at least part content item is set to the minimum of: a capping limit; the time measurement of how long the at least part content item was rendered and outputted for display to the audio-visual outputting arrangement, wherein the capping limit is higher for a period correlating to a statistically high confidence level of user presence when compared to a period correlating to a statistically low confidence level of user presence; and the average content item duration. a capping limit;