Formulation of hypotheses

Definition

 * A Hypothesis'' is an assumption whose validity we must verify before proceeding with further scientific work.
 * Provisional theory is based on descriptive research/statistics, clinical observations, analytical studies, laboratory research, theoretical modeling.

Differential method

 * If the frequency of occurrence of a disease in two comparative populations (sets) is significantly different' and if it is possible to identify a factor that is present in one set and not in the other, then we can label this factor as  'cause of disease'.
 * Example: higher incidence of ca of the cervix in married women - and vice versa lower' incidence in nuns.

Match Method

 * If we can find a common factor in a number of different populations that are characterized by the occurrence of a disease, then this factor could be the 'cause of the disease.
 * Example: Semmelweis came to the conclusion that the cause of teenage fever was some kind of "dead poison" found 'on the hands of the attending obstetric staff.

Method of analogy

 * If there are ``certain similarities in the distribution of the observed disease with another disease for which we have more complete information, it would be possible to judge that both diseases have ``some common causes. We use a deductive way of thinking.

Companion Difference Method

 * The change in the frequency of the disease occurs in parallel with the change in intensity of the given factor.
 * Example: incidence of lung carcinoma increases with the number of cigarettes smoked'.

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Related Articles

 * Methodology in epidemiology