RIOT Scan takes the text provided by the user and subjects it to recursive analysis in order to calculate various indices, most of which are inspired by the Composite Variability Index of Dr. Colin Martindale. Other indices are calculated pertaining to the words in the text as well (such as average word length). The indices are as follows:

• SixLetter – the percentage of words that are greater than six letters long.
• Unique_Ratio – the ratio of unique words to total words. Score is provided in the form of a percentage.
• Hapax_Ratio – the ratio of words that appear only once in a body of text to total words. Score is provided in the form of a percentage.
• Unique_Ratio_Sent – like Unique_Ratio, but at the sentence level. Score is provided in the form of a percentage.
• Hapax_Ratio_Sent – like Hapax_Ratio, but at the sentence level. Score is provided in the form of a percentage.
• AvgWordLengthPerSentence – average word length at the sentence level.
• AvgWordLengthOverall – average word length for the entire body of text.
• COVWordLength – coefficient of variation for word length.
• AvgSentenceLength – average number of words per sentence.
• COVSentenceLength – coefficient of variation for number of words per sentence. Can also be referred to as the coefficient of variation for “phrase length”.

If your output has any results that are listed as “NaN” (or “.”), this stands for “Not a Number”. This is typically the result of no variance in the language used in a body of text (e.g., a body of text consisting of only one word, or the same word over and over).