text of works from European languages, although the numerical differences between Voynichese and Mandarin Chinese pinyin look larger than those between Mandarin Chinese pinyin and European languages. Practically no words have fewer than two letters or more than ten. Some words occur in only certain sections, or in only a few pages; others occur throughout the manuscript. Few repetitions occur among the thousand or so labels attached to the illustrations. There are instances where the same common word appears up to three times in a row (see Zipf's law). Words that differ by only one letter also repeat with unusual frequency, causing single-substitution alphabet decipherings to yield babble-like text. In 1962, cryptanalyst Elizebeth Friedman described such statistical analyses as "doomed to utter frustration". In 2014, a team led by Diego Amancio of the University of São Paulo published a study using statistical methods to analyse the relationships of the words in the text. Instead of trying to find the meaning, Amancio's team looked for connections and clusters of words. By measuring the frequency and intermittence of words, Amancio claimed to identify the text's keywords and produced three-dimensional models of the text's structure and word frequencies. The team concluded that, in 90% of cases, the Voynich systems are similar to those of other known books, indicating that the text is in an actual language, not random gibberish. Linguists Claire Bowern and have applied statistical methods to the Voynich manuscript, comparing it to other languages and encodings of languages, and have found both similarities and differences in statistical properties. Character sequences in languages are measured using a metric called h2, or second-order conditional entropy. Natural languages tend to have an h2 between 3 and 4, but Voynichese has much more predictable character sequences, and an h2 around 2. However, at higher levels of organization, the Voynich manuscript displays properties similar to those of natural languages. Based on this, Bowern dismisses theories that the manuscript is gibberish. It is likely to be an encoded natural language or a constructed language. Bowern also concludes that the statistical properties of the Voynich manuscript are not consistent with the use of a substitution cipher or polyalphabetic cipher. As noted in Bowern's review, multiple scribes or "hands" may have written the manuscript, possibly using two methods of encoding at least one natural language. The "language" Voynich A appears in the herbal and pharmaceutical parts of the manuscript.