In https://www.wikidata.org/wiki/Wikidata:Project_chat#Precision_of_date a user describes that he would have expected "publication date = 2013" in the normal Wikidata interface to be also shown as 2013 in the webinterface of the query service. Currently, the webfrontend however ignores the data about the precision completely and outputs "Jan 1, 2013"

Example query:
https://query.wikidata.org/#SELECT%20%3Finstance_of%20%3Fpublication_date%20WHERE%20%7B%0A%20%20%3Finstance_of%20wdt%3AP31%20wd%3AQ26973022.%0A%20%20%3Finstance_of%20wdt%3AP50%20wd%3AQ44942293.%0A%20%20OPTIONAL%20%7B%20%3Finstance_of%20wdt%3AP577%20%3Fpublication_date.%20%7D%0A%7D%0ALIMIT%2050