On the Quantitative Evolution of the Harry Potter Books
Harry Potter and the Order of the Phoenix was released just a few days ago, and I am already eagerly awaiting the sixth volume in this superb series from J. K. Rowling. Looking at the stack of five books that I already have, it was pretty obvious that the number of pages have steadily been increasing with every published volume. So I naturally wondered how many pages the next volume was likely to have.
Here is a summary of what we know about the number of pages in the existing volumes:
| Volume | Title | Number of Pages | Number of Words | Thickness in mm | Weight in grams |
|---|---|---|---|---|---|
| 1 | Harry Potter and the Philosopher's Stone | 223 | ? | 11.5* | ? |
| 2 | Harry Potter and the Chamber of Secrets | 251 | ? | 14* | ? |
| 3 | Harry Potter and the Prisoner of Azkaban | 317 | ? | 17.5* | ? |
| 4 | Harry Potter and the Goblet of Fire | 636 | ? | 28* | ? |
| 5 | Harry Potter and the Order of the Phoenix | 766 | ~225,000 | 59 | ? |
| 6 | Harry Potter and the ? | (880) | ? | ? | ? |
As we can see from the above data table, it is simple enough to do a linear extrapolation to "predict" how many pages the sixth volume in the series ought to have. From the extrapolation, we obtain the value of 880. You can see this in the graph below.
It is possible to select a different extrapolation model, but I chose linear because the exact trend is difficult to follow. I do not see much of a case for quadratic, exponential or any other fits to the data set.
Also, much of the data in the above table is still unavailable. Please contact me if you are able to provide any of the missing data. Specifically I am looking for:
- If you know the total number of words that were contained in each volume, or if you know where I may obtain this information, or
- If you have the original hardcover European or American editions for the first four volumes, that you send me the thickness and the weight of each volume
My thickness measurements above are actually incorrect because the paper type and quality varies drastically from volume to volume in the domestic paperback editions in India. I have noted these incorrect measurements using asterisks (*). It is quite possible that either of the above data series might provide a better mathematical prediction model than the total number of pages.
The data on this page was compiled with the help of Navin Kadambi.