Types of Hypothesis

Introduction:

               In any test of hypothesis we begin with some assumptions about the population from which the sample is drawn.  This assumption may be about the form of the population or about the parameters of the population.  Such an assumption is logically drawn. This assumption is called Hypothesis.

            A statistical Hypothesis is defined as a tentative conclusion logically drawn connecting the parameter or the form of the distribution.
Eg:-  The sample is drawn from a normal population with mean=30 and standard deviation=5 
There are different types of Hypothesis. They are :-

Types of Hypothesis:

1)      Simple and Composite Hypothesis
A hypothesis may be simple or composite.  If a hypothesis is concerning the population completely such as functional form and the parameter, it is called simple hypothesis.  If a hypothesis is not simple then it is Composite.
Example:-
The hypothesis “Population is normal with mean 15 and standard deviation 5” is a simple hypothesis where as the hypothesis “population is normal with mean=15” is a composite hypothesis. 
2)      Parametric and Non Parametric
A hypothesis, which only specifies the parameters of the probability density function, is called parametric hypothesis. If a hypothesis specifies only the form of the density function in the population, it is called a non- parametric hypothesis.
Example:-
The hypothesis “ Mean of the population is 15” is parametric where as the hypothesis “ population is normal” is non- parametric.
3)      Null and Alternative Hypothesis
A null hypothesis can be defined as a statistical hypothesis, which is stated for acceptance.  It is the original hypothesis. Any other hypothesis other than null hypothesis is called Alternative hypothesis..  When null hypothesis is rejected we accept the alternative hypothesis. Null hypothesis is denoted by H₀ and alternative hypothesis is denoted by H₁.