Monday, March 11, 2013

More Cumulative Distribution Tabs

This is a recent post from, a blog of vintage photographs. This image from 1933 shows a woman deftly gluing alphabet tabs on, what appears to be, a dictionary. We've seen earlier how such tabs represent the cumulative distribution function of the first letter of the words in English. The close-up below show the dictionary to the woman's left. The tabs for letter groups run from Z to A from left to right. For our use, we flip it over allowing the alphabet to run properly from A to Z.
The tabs then show relatively few English words beginning with the last letters of the alphabet.
When flipped over, we can see the tabs form cumulative distribution function just as the printed pages showed in our earlier post. More details on these cumulative distribution images can be found in my paper available here.


Pat B said...

Kind of difficult to interpret much since there is not a tab for each letter; and if memory serves me correctly, some letters were tabbed alone, others in three or more (IJK?)

Robert W. Jernigan said...

Good point. You're right, dictionaries did group several letters together in one tab. The individual letter tabs are better seen in the earlier posts I mentioned. These tabs show us the relative frequencies of the tab groups spaced along the alphabet like numbers on a number line.