4.1 Document size

  

Figure 2: Size distribution of Word, PowerPoint, and Excel documents. Shown are documents with sizes up to 180 KB.

 

Table 2: Document size statistics.

	Application
Statistic	Word	PowerPoint	Excel
average (KB)	196.24	891.48	115.02
stdev (KB)	528.44	2145.35	438.70

Table 2 shows general statistics for Word, PowerPoint, and Excel documents¹. The most striking aspects of the data are the large average size of the documents and the large standard deviations of our sample.

Figure 2 shows the size distribution of Word, PowerPoint, and Excel documents. The histogram plots documents with sizes up to 180 KB. We observe that the distributions have the same general shape: a cluster around a common small value with a fairly long tail.

Figure 3 characterizes the distributions' tails by plotting document size frequencies for documents larger than 100 KB on a log-log scale. The linear fit² of the transformed data ( $y \sim x^{-1.7124}$) with R² = 0.8938 suggests that the tail of the size distribution closely follows a power-law distribution, which is consistent with the large standard deviations of Table 2. The log-log scale histograms for the individual Word, PowerPoint, and Excel documents are not shown here since they are all similar to the cumulative distribution, with linear fits of $y \sim x^{-1.5254}$, $y \sim x^{-1.332}$, $y \sim x^{-1.7485}$, and R²=0.8612, R²=0.8352, and R²=0.8226, respectively.

Interestingly, these results are similar to the findings of Cunha et. al. [7] where the size of HTML-based Web documents was found to follow the power-law distribution. However, while Cunha et. al. found that most HTML documents are quite small (usually between 256 and 512 bytes), Office documents tend to be much larger. Common sizes of Word and Excel documents size range from 12 KB to 24 KB, and common PowerPoint documents range from 48 KB to 80 KB.

  

Figure 3: Size distribution of larger Office documents on a log-log scale. Document size frequencies are measured with 16384 byte bins.