The collection is composed of manuscript and typescript correspondence (largely letters from) Sir Godfrey Thomson between 1937 and 1954. The material includes: sheaf of correspondence (dated Feb. 1937 - Dec. 1937), Thomson to Ledermann / Horst (36 letters/postcards/items); sheaf of correspondence (dated New Years Day 1938 - Dec. 1938), Thomson to Ledermann, and some Ledermann to Thomson (58 letters/postcards/items) including one M.S. Bartlett to Thomson (a typescript letter on estimation); and, a sheaf of correspondence (dated 1939 - 1954), Thomson to Ledermann, and Thomson to Herdan (circa 50 letters/postcards/items).
The mathematical subjects within the letters range from factorial analysis, pentad criterion, multivariate selection, correlation between estimation and selection, Bartlett's method of estimating factors, boundary conditions, minimum trace and minimum Thorstone rank, tetrad criterion, univariate selection, profile correlations and Thurstone residues, Spearman matrix, and reciprocity of persons and tests. Other topics include: social invitations; advice on articles for journals; lists of books for purchase; correlations between persons; and, tests results.
Among the letters too there are occasional off-prints (usually single pages) from academic journals, and transcripts of formulae and estimates.