For Ada Lovelace Day: Janet Lane-Claypon

March 24, 2010 at 8:30 am (Good Science, Miscellaneous) (, )

In honour of Ada Lovelace (one of the world’s first computer programmers), the website aims to draw attention to the achievements of women in technology and science on March 24th – Ada Lovelace Day – with an international day of blogging. Here is my contribution.

Janet Elizabeth Lane-Claypon was “an English physician and one of the founders of the science of epidemiology”, who led the use of cohort studies and case-control studies.

Doctor-doctor Lane-Claypon (Janet Lane-Claypon was both a medical doctor and a PhD) published a pioneering study in 1912 that looked at two groups of babies. The babies in these groups were fed either cow’s milk or breast milk. This was an early cohort study.

Lane-Claypon found that those babies fed breast milk gained more weight, and she used statistical methods* to show that the difference was unlikely to occur by fluke alone. She also investigated whether something other than the type of milk could account for the difference, an effect known as confounding.

*As well as her other achievements, Lane-Claypon was seemingly the first to use statistical methods (the Student’s t test) to analyse epidemiological data. This was apparently prompted by a Dr. Major Greenwood  of the Lister Institute, who was credited in a footnote to the 1912 cohort study.

One of the advantages of a cohort study is that the design does not require strict random assignment of subjects. Where randomization is impractical or unethical, a cohort study may prove useful.

When Richard Doll and Austin Bradford Hill concluded that cigarette smoking was an important cause of lung cancer, they were not believed. They designed a cohort study and:

“within two and a half years the pair had enough evidence to show an association between smoking and lung cancer and scientists started to take notice. At the end of the five years everyone concerned in the cancer research field accepted it.” [Link]

This is just one example of the value of the cohort study – a form of investigation which was popularised by Janet Lane-Claypon.

Lane-Claypon went on to develop the case-control study. She conducted a large study of women who had previously been diagnosed as having breast cancer and an equal number of women free from the disease.

Through this investigation, Lane-Claypon identified some of the risk factors for breast cancer, including age at menopause and age at first pregnancy – which are still recognised as risk factors now.

Janet Lane-Claypon made important contributions to breast cancer research, and to epidemiology, and deserves to be remembered for her achievements.


Here are some suggestions for further reading:

This commentary from Warren Winkelstein, Jr discusses the “three firsts” of Lane-Claypon – the first retrospective (historical) cohort epidemiologic study, describing confounding and analyzes her data to investigate the possibility that it explained the findings, and using Student’s t test to evaluate the observed differences in weight (in the cohort study comparing breast milk to cows milk).

Here are some publications on Open Library that may be of interest.


  1. zeno said,

    I’m reading a fascinating book, which, although I haven’t come across a mention of Janet Lane-Claypon, tells the story of Major Greenwood, Austin Bradford Hill and other well-known names from statistics such as Pearson and Fisher and their influence on medical trials: Taking the Medicine by Druin Burch. On the chapter about Archie Cochrane at the moment.

  2. Felix said,

    “one of the world’s first computer programmers”

    Once you have accepted the proposition that she was a computer programmer, who is there, chronologically, to challenge her for the honour of being the first?

  3. jdc325 said,

    You’re quite right Felix – the words “one” and “of” seem to be redundant.

    Thanks for commenting.

  4. The Year In Nonsense. And Stuff. « Stuff And Nonsense said,

    […] – we are all irrational. I also mentioned again one of my unsung heroes of science – Janet Lane-Claypon (this time for Ada Lovelace […]

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