user63709: As described in BIP-113. Wouldn't the last 12 blocks bring us closer to a one-hour offset (ie 120min, midpoint 60)?

user63709: It is a median, not an average, thus it selects the 6th block's timestamp after sorting.
If you're a non-native English speaker, international maths heuristics can be quite tricky. Double-check on the Internet before translating into your head.

user208: BIP 113's goal is not to aim for a specific offset.
Its goal is guaranteeing monotonicity (treating every block's timestamp as strictly larger than the timestamp of each of its ancestors). It does this by leveraging the existing consensus rule which states that the median of the timestamp of a block has to be strictly larger than the median of its 11 predecessors.
As to why the number 11 eleven was chosen in that existing consensus rule, we don't know. It was chosen by Bitcoin's creator.

63709: <p>As described in <a href="https://github.com/bitcoin/bips/blob/master/bip-0113.mediawiki" rel="nofollow noreferrer">BIP-113</a>. Wouldn't the last 12 blocks bring us closer to a one-hour offset (ie 120min, midpoint 60)?</p>
 63709: <p>It is a <a href="https://en.wikipedia.org/wiki/Median" rel="nofollow noreferrer">median</a>, not an <a href="https://en.wikipedia.org/wiki/Average" rel="nofollow noreferrer">average</a>, thus it selects the 6th block's timestamp after sorting.</p>

<p>If you're a non-native English speaker, international maths heuristics can be quite tricky. Double-check on the Internet before translating into your head.</p>
 208: <p>BIP 113's goal is <strong>not</strong> to aim for a specific offset.</p>

<p>Its goal is guaranteeing monotonicity (treating every block's timestamp as strictly larger than the timestamp of each of its ancestors). It does this by leveraging the <strong>existing</strong> consensus rule which states that the median of the timestamp of a block has to be strictly larger than the median of its 11 predecessors.</p>

<p>As to why the number 11 eleven was chosen in that existing consensus rule, we don't know. It was chosen by Bitcoin's creator.</p>
