When you upload a Census National Index Extract file, you will be given the opportunity to download the Aggregated Distribution file which is created from the National Index Extract file.
Alternately, if you are a Windows user, you can download a program that will convert a National Index Extract file into a an Aggregated Distribution File on your own PC.
The Aggregated Distribution file can be uploaded instead of the National Index Extract file if you wish to create distribution maps in a subsequent session. Because the Aggregated Data File is considerably smaller than the National Index file, it is much quicker to upload.
The format of the Aggregated Distribution File downloaded from this facility when you upload a National Index File is 'Tab delimited text', which uses TAB characters to separate the three fields in each record, as follows:-
Note that the TAB character is non-printing, and is represented by the in the above example. The 'Tab delimited text' format is convenient for loading into a spreadsheet for editing or further analysis.
The three fields in each record are the Surname, the Chapman code for the 'Old' County, and the number associated with this county. When the Aggregated Distribution File is downloaded from this site, or created with the ukdistag program which can be downloaded from this site, this number is the count of individuals with the Surname in the County. However, it could be some other figure, such as a population density (e.g. 0.000013) providing you calculate that figure and create an Aggregated Distribution File of your own.
In addition to the data, the file can also contain an optional title, which identifies the data in the file. The title appears on the first line of the file, thus:-
The title must appear on the first line of the file and it must be preceded by Title= which identifies the record as the title record.
Creating Your Own Aggregated Distribution File
If you want to create distribution maps from a source of data other than the LDS 1881 British Census CDs, you can do so, but you will need to create your own Aggregated Distribution file.
As noted above, the file is a plain text file. You may use either TAB characters or commas (,) to separate the three fields in each record, as follows:-
The three fields in each record are:
The number can be a count of the number of people in the county with the surname, or any other meaningful measurement, such as density or frequency of the surname.
If you have data for the Channel Islands you can plot these either for the individual islands of Jersey, Guernsey, Alderney and Sark, or as a single entry for the Island group. Take care that you use either CHI or the individual island codes, JSY, GSY, ALD and SRK. If you do include CHI and any of the codes JSY, GSY, ALD or SRK then the data for the individual islands will not be plotted and will appear as Other in the Legend.
The easiest way to create your own Aggregated file is using a spreadsheet. Your worksheet should contain 3 columns, corresponding to the 3 fields in each aggregated record. If you want to include a title record in your file (see above), this should be placed in cell A1. When you have entered all your data save the file as a Text (Tab Delimited) file or as a CSV file. This file can then be uploaded for analysis, using the form on the Aggregated Distribution File Upload page. Some spreadsheets will enclose fields in double quotes ("). That's OK - the upload process strips any double quotes from the file being uploaded. If you are entering a title, it should be placed in cell A1, according to the rules specified above.
The table below shows the Chapman Codes and the full names of the counties of England, Wales, Scotland and Ireland.
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