DATE IMPUTATION

Problem

Before 1919 (incl), the publication date of DE patents is missing. Frontier is fuzzy, patents publication numbers are not exactly chronological but nearly. This makes it hard to manually find the latest publication number for each vintage. Number seem to be given based on the "Patentdatum".

Approach

We look in the corpus of patents to find the latest publication number for each given year from 1877 to 1920. We use the patent gazette published par the German patent offices ("PatentBlat") and consider the largest publication number specified under section "Erteilungen". The gazette is published weekly and we consider either week 52 or week 53 of each year from 1878 to 1919 (and 51 for 1918). From these benchmark patents, we carry forward the year of publication.

Warning

This method is not applicable for patents published earlier than 1883, hence for years 1877-1882, we manually look for patents with publication date in late December and arbitrarily select a benchmark.

Results

Publication year	Benchmark publication number
1877	DE-1877-C*
1878	DE-3297-C*
1879	DE-8460-C*
1880	DE-12116-C*
1881	DE-16547-C*
1882	DE-20544-C*
1883	DE-26025-C
1884	DE-30543-C
1885	DE-34561-C
1886	DE-38569-C
1887	DE-42451-C
1888	DE-46348-C
1889	DE-50707-C
1890	DE-55460-C
1891	DE-61010-C
1892	DE-66910-C
1893	DE-73340-C
1894	DE-79528-C
1895	DE-85240-C
1896	DE-90750-C
1897	DE-96190-C
1898	DE-101760-C
1899	DE-109190-C (we use DE-109189-C as DE-109190-C is missing)
1900	DE-117765-C
1901	DE-128268-C
1902	DE-139092-C
1903	DE-149056-C
1904	DE-158245-C
1905	DE-167845-C
1906	DE-180900-C
1907	DE-194320-C
1908	DE-206135-C
1909	DE-218130-C
1910	DE-230230-C
1911	DE-242870-C
1912	DE-255770-C
1913	DE-269260-C
1914	DE-281820-C
1915	DE-290010-C
1916	DE-296016-C
1917	DE-303620-C
1918	DE-310930-C
1919	DE-318790-C