Broader, deeper, and harder to coach
The popularity of the 1916 scale in inter-war America is what made coaching a real risk; Form L stayed closer to the 1916 content while Form M was new material designed to be equivalent to it in difficulty, range, reliability and validity.2
Larger and more representative — by 1930s standards
Note on the sample size: secondary sources give "3,000" and "3,200"; the often-repeated 3,184 could not be traced to a primary source here. Confirm against Terman & Merrill (1937) before quoting an exact figure.1,4
One general factor — or several?
The Stanford-Binet line
Take Form L. Then retest on Form M.
Each age level has a twin item of matched difficulty. Remembering the Form L answer doesn't help on Form M — the point of the design.
Sources cited on this page
- [1]Standardization of Stanford Binet Intelligence Scale — secondary summary citing Terman & Merrill (1937) and Roid (2003). Assignment Point.assignmentpoint.com
- [2]Science Museum Group. Test materials for Revised Stanford-Binet tests (Forms L and M).collection.sciencemuseumgroup.org.uk
- [3]Smithsonian National Museum of American History. Complete Test Material for Form L, Revised Stanford-Binet Scales.americanhistory.si.edu
- [4]Kuhlenschmidt, S. Stanford-Binet 1937 and others (manual excerpts and notes). Western Kentucky University.people.wku.edu
- [5]Smithsonian National Museum of American History. Record Booklet — Form M for the Revised Stanford-Binet Scale (Houghton Mifflin, 1937).americanhistory.si.edu
- [6]McNemar, Q. (1942). The revision of the Stanford-Binet Scale: An analysis of the standardization data. Boston: Houghton Mifflin. NLM Catalog.ncbi.nlm.nih.gov/nlmcatalog
- [7]Jones, L. V. (1949). A factor analysis of the Stanford-Binet at four age levels. Psychometrika, 14(4), 299–331.doi:10.1007/BF02289194
- [8]Stone, J. S., III (thesis). The Stanford-Binet, Form L-M, and the Wechsler Intelligence Scale for Children. University of North Texas Digital Library.digital.library.unt.edu
- [9]Wikipedia contributors. Quinn McNemar (accessed 29 Sept 2026).en.wikipedia.org
- [10]Stanford-Binet Intelligence Test. In The SAGE Encyclopedia of Abnormal and Clinical Psychology (2017). SAGE.sk.sagepub.com
- [11]Science Museum Group. 'Form M Revised Stanford-Binet Scales', IQ test, United States, 1937 (object record).collection.sciencemuseumgroup.org.uk
Primary source: Terman, L. M., & Merrill, M. A. (1937). Measuring Intelligence: A Guide to the Administration of the New Revised Stanford-Binet Tests of Intelligence. Boston: Houghton Mifflin.5
Related historical IQ tests
Terman's public-domain first edition, with interactive items.
Two years later, with a deviation IQ and a verbal–performance split.
The modern descendant of the Stanford line.
The first American Binet.
Seven abilities, not one — the year after this revision.
Built to cover the Binet's functions in a class setting.