# T1 - Lithium for maintenance treatment of mood disorders.

Calculate the U statistic as the smaller of U_{a} and U_{b}. For n_{2}≤ 20, Mann-Whitney tables are used to determine the probability, based on the U, n_{1} and n_{2} values. This probability is then used to reject or fail to reject the null hypothesis. If n_{2} > 20, the distribution of U rapidly approaches the normal distribution and the following apply:

## THE SEROTONIN HYPOTHESIS OF MAJOR DEPRESSION

### The somatic marker hypothesis ..

For example, let us say that we wanted to test the 5-HIAA (a serotonergic metabolite) levels in the cerebrospinal fluid (CSF) of depressed individuals.

### The findings supported the mood maintenance hypothesis in ..

This is a test of independent samples. The measurements may be continuous data, but the underlying distribution is either unknown, or known to be non-normal. In either case, the data can be ranked and analyzed without the constraint of having to assume a known population distribution.**Example:** Three different plants manufactured the same garment style. Variation in garment length was a customer concern. Length was measured to the nearest 1/4″. Within each plant, only four measurement increment values were obtained. This lack of measurement sensitivity indicated that ranking the data was preferred to assuming normality. The null hypothesis is that the population medians are the same. H_{o}: M_{1} = M_{2} =… = M_{n}. The following table shows data coded as deviations from a common reference value.