A Generalization of the «Lady-Tasting-Tea» Procedure to Link Qualitative and Quantitative Approaches in Psychiatric Research


  • Bruno Falissard Inserm, U669, Paris, France
  • Daniel Milman AP-HP, Service de Psychiatrie de L’enfant et de L’adolescent, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
  • David Cohen CNRS UMR 8189 Psychologie et Neurosciences Cognitives et Université Paris VI, Paris, France




Randomization, power calculation, permutation test, clinical records


In Fisher’s “The Design of Experiments”, a trial was designed to test a lady’s claim to be able to discriminate whether the milk or the tea was added first to a cup. In this trial, eight cups are poured, four with milk first and four with tea first. They are then presented in random order to a subject who has to divide them into two sets of 4, according his/her belief about the "treatment" received. The present paper generalizes this design so that a hypothesis concerning the existence of two sub groups in a set of psychiatric patient records (whether written, audiotaped or videotaped) can be tested rigorously from a statistical point of view. Tables are proposed to enable power and sample size calculations. A real example is presented; it shows that psycho-dynamically oriented professionals are able to discriminate seven healthy adults who have experienced a sibling’s cancer during childhood or adolescence from seven matched controls. This method is particularly suited to small sample studies that explore elusive clinical hypotheses traditionally tackled with qualitative methodologies.


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How to Cite

Falissard, B., Milman, D., & Cohen, D. (2013). A Generalization of the «Lady-Tasting-Tea» Procedure to Link Qualitative and Quantitative Approaches in Psychiatric Research. International Journal of Statistics in Medical Research, 2(2), 88–93. https://doi.org/10.6000/1929-6029.2013.02.02.02



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