Since the passenger manifests are hand-written forms, there are great discrepancies in quality. The quality of the data may suffer as a result of a number of factors:
• Poorly legible or illegible entries. This may be due to damaged lists, illegible handwriting, corrections or deletions etc.
• Unclear entries. In the late 19th century in particular the clerks were not very careful (entries written in the wrong place, lines in the wrong place, one entry for several people or the whole family etc.).
• The entries in the passenger manifests were often based on information given orally by the emigrants themselves. This information was often misheard or deliberately altered (e.g. Americanization of spellings or professions), leading to a further loss of quality in the original data.
• The amount of information on emigrants differs depending on the year of emigration. At the beginning of the 19th century the passenger manifests contained 11 entries for each emigrant. At the beginning of the 20th century the number of entries was 40.
• The information on the manifests is not always the same for each period. For example, the place of origin of the emigrant is not always recorded.
The German Emigrants Database tries to point out any recognizable problems with the data quality with a notation system.