de Student

The brewer

Student’s t distribution. Student’s t probability distribution allows estimating the value of the population mean of a random variable that follows a normal distribution when the parameter is extracted from a small sample and the population variance is unknown.

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pragmatic clinical trial

Like life itself

Pragmatic clinical trial. We all know how difficult it is to make a new drug available to people who can benefit from it. From the moment a promising molecule is identified and somebody thinks that it may be useful, until it can be bought in a pharmacy, a long journey goes by that, at present, usually does not last less than 10 or 12 years. During this long journey, the future drug, after its initial development phase, enters the thorny path of the preclinical phase, with studies in cell or animal models, followed by a gradual use in humans to…

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tamaño muestral

A strenuous effort, though unnecessary

Factors that condition the sample size. The need to perform a correct calculation of the sample size necessary for a study is reviewed, as well as the main factors that influence the sample required to demonstrate the effect considered relevant from a clinical point of view.

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The tribulations of maturity

Correct use of NNT. The NNT was designed to assess the beneficial effect of a treatment to reduce the risk of an unpleasant event occurring in an intervention group of interest, always with respect to what was observed in a control group. Some of the aspects to take into account to use it correctly are reviewed.

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Fisher's exact test

A story of tea and numbers

Fisher’s exact test. Fisher’s test is the exact method used when you want to study if there is an association between two qualitative variables, that is, if the proportions of one variable are different depending on the value of the other variable. Today we are going to remember one of the most beautiful stories, in my humble opinion, in the history of biostatistics. Although surely there are better stories, since my general historical ignorance is greater than the number of decimal places of the number pi. A story of tea and numbers Imagine we are at Rothamsted Station, an agricultural…

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