What+is+SLA+-+Latent+Semantic+Analysis

Latent Semantic Analysis (LSA)
Landauer & Dumais (2004): //A general theory of "acquired similarity and knowledge representation"// (p. 1).

Landauer and Dumais used the //Grolier Encyclopedia,// an electronic text for young students, to analyze 30,473 articles with a mean text length of 151 words. (Some articles were only one sentence long, e.g., "Constantinople; see //Istanbul//," and longer articles were cut off at 2,000 characters.) The words were placed into a matrix, each column representing an article, and each row one of 60,768 word-types that appeared in at least 2 articles. Each cell contained the frequency with which a word appeared in that article:

//Table based on Landauer & Dumais, Figure 2, p. 13.//
 * Word/Article || 1 || . || . || . || . || . || . || . || 30,000 ||
 * 1 || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ ||
 * . || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ ||
 * 60,000 || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ ||
 * 60,000 || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ ||
 * 60,000 || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ ||
 * 60,000 || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ ||
 * 60,000 || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ || _ x_ ||

//NEXT//

Landauer, T. K., & Dumais, S. T. (2004). A solution to Plato's problem: The Latent Semantic Analysis theory of acquisition, induction and representation of knowledge. Available at http://lsa.colorado.edu/papers/plato/plato.annote.html.