Wikipedia:Reference desk/Archives/Computing/2020 September 29

= September 29 =

YouTube and COPPA
On YouTube, there are a number of ways for me to find and re-watch a video. I can add it to the "watch again" play-list (or create a custom category); I can "like" it, adding it to a list of "liked videos" that I can browse to find it, or I can browse my "History" to find it again. Except: if the video is considered to be "for kids", the first option ("watch again" / custom playlist) is disabled in order to comply with COPPA. But the other methods ("like" and "history") are still available. What is the reason for this discrepancy? I've read YouTube's own explanation, plus our articles on YouTube and Children's Online Privacy Protection Act, but can't see a clear reason or explanation why the former would be illegal but the latter OK.Iapetus (talk) 13:10, 29 September 2020 (UTC)
 * I don't think anyone can give you a reason that isn't either speculation or a legal opinion. Since COPPA was enacted in 2000 and is consequently nothing new, an obvious guess would be that Google has decided it's too dangerous to keep playing scofflaw with some part of it. Possibly Google's shadow profiles of children are illegal even in the privacy-careless USA (Google was given the biggest fine in history of COPPA last year). It could be that Google has decided that, rather than comply with the law and not track users who might be children (which might mean being unable to track anybody), it will not track users watching videos that children are likely to watch. Since your playlists are not local and are data that Google collects, that would explain why you can't add such videos to a playlist. A way to get past this would be to switch to a 3rd party YouTube website / app. Elephas X. Maximus (talk) 19:56, 29 September 2020 (UTC)
 * You're logged in to a Google account, and to create an account you have to say you're at least 13, so that satisfies the COPPA requirement. I think YouTube playlists can be made public, right? That would probably be why the playlist function is disabled. Doing that might not be absolutely strictly required by the law, but it's not going to hurt them to be on the safe side. There's also a public relations aspect, as YouTube has gotten bad press in recent years relating to videos intended to "trick" kids as well as creepy adults frequenting videos depicting children. --47.146.63.87 (talk) 21:59, 29 September 2020 (UTC)

Sorting
69.5.123.49 (talk) 22:50, 29 September 2020 (UTC)
 * 1) Why is bubble sort slower than selection sort and insertion sort?
 * 2) Why is an optimized insertion sort faster than selection sort?


 * Even when the number of comparisons is the same, the number of array accesses for bubble sort is 2 to 4 times the number of comparisons, on average $$\approx \tfrac{3}{2}n^2$$, while for selection sort and optimized insertion sort it is linear in $$n$$ (the length of the array). Which of the latter two algorithms is faster on average depends on details of the implementation. --Lambiam 16:52, 30 September 2020 (UTC)
 * What? How is selection or insertion not quadratic? —Tamfang (talk) 02:20, 4 October 2020 (UTC)


 * These sound like homework questions. How would you go about comparing two algorithms?  Have you run any tests?  What did you find?  If your class uses a textbook, does it say anything about this topic?  Fwiw, The_Art_of_Computer_Programming discusses and compares them in detail.  2601:648:8202:96B0:0:0:0:DDAF (talk) 19:38, 30 September 2020 (UTC)