Alternative hypothesis

economic-dictionary

The alternative hypothesis is the alternative assumption to the null hypothesis formulated in an experiment and / or investigation. This arises as a result of a certain investigation carried out on a population or sample.

Understood in a simple way, the alternative hypothesis represents the conclusion that the researcher wants to demonstrate or affirm after his study. This is expressed with the expression "H1" and will generally represent the opposite of the null hypothesis.

The scientific method, contrary to what one might think, does not try to prove the alternative hypothesis (conclusion reached through research). What the scientific method claims is that the opposite of the alternative hypothesis (null hypothesis) is not true. In this way, the alternative hypothesis would be demonstrated.

Example of hypothesis testing

Suppose that a researcher has carried out a study on the average monthly salary in a certain neighborhood of a city. Imagine that of the population of that neighborhood, the researcher has surveyed 1,000 people, concluding that the average monthly salary per capita is 1,500 CU (currency units).

Therefore, the researcher wants to test whether that average monthly salary is equal to CU1,500. (conclusion of the study and therefore alternative hypothesis) or if, on the contrary, the average monthly salary is different from CU1,500. (conclusion contrary to that of the study that is intended to deny and therefore null hypothesis)

The contrast to be carried out would be the following:

H0: Average monthly salary is other than CU1,500.

H1: The monthly salary is equal to CU1,500.

As we can see, the alternative hypothesis (H1) is the conclusion reached by the researcher. To prove it, the researcher will try to prove that the opposite of his alternative hypothesis (null hypothesis, H0), is not true. As a conclusion, we can deduce that the formulation of the alternative hypothesis is the one that will lead us to the formulation of the null hypothesis.

Conclusions of the hypothesis test of the example

After the test carried out, the researcher may or may not reject the null hypothesis (thus proving that the alternative hypothesis is true). The correct way to discuss the result of a hypothesis test is to always speak in terms of the null hypothesis.

If the hypothesis has been rejected, the following statement can be used, "in light of the data and after the result obtained through the hypothesis contrast carried out, sufficient evidence is available to be able to reject the null hypothesis." Therefore, the conclusion would be that the average monthly salary is equal to CU1,500. On the contrary, if we have not been able to reject the hypothesis of the test carried out, the following statement could be used, “in light of the data and after the result obtained through the test of hypotheses carried out, there is not enough evidence to be able to reject null hypothesis ”. If so, the conclusion would be that the average monthly salary is not equal to CU1,500.

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