In: Statistics and Probability
The National Institute of Mental Health published an article stating that in any one-year period, approximately 9.5% of American adults suffer from depression or a depressive illness. Suppose that in a survey of hundred people in a certain town, seven of them suffered from depression or a depressive illness. Conduct a hypothesis test to determine if the true proportion of people in that town suffering from depression or a depressive illness is lower than the percentage in the general adult American population
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Answer:
The null hypothesis
can be stated as shown below:

That mean, the proportion of people suffering from depression in the town is at least 9.5% of American adults.
And, the alternative hypothesis
can be stated as shown below:

That mean, the proportion of people suffering from depression in the town is less than 9.5% of American adults.
Here, x is the number of successes from total number in
the sample. Therefore, x is
.
iHere, n is the total number in the sample. Therefore,
n is
.
Point estimate
can be calculated as shown below:

The calculation of
is shown below:

The distribution for
is shown below:

Therefore,

To find p-value in excel, enter value of p
and
as shown below:

Now, calculate z-statistics in cell B4 by inserting
formula
.
The screenshot is shown below:

Finally, calculate p-value as shown below:

Hence, p-value is
.
Decision: Do
not reject the null hypothesis
.
Reason for the decision: Reject
because
. But here, p-value is greater than
alpha level 0.05. That is,

Conclusion: It is given that the p-value is 0.196. Therefore, for 5% of established alpha level it can say that do not reject the null hypothesis because p-value is greater than alpha level 0.05. Hence, there is no sufficient evidence to insure that the proportion of people suffering from depression in the town is less than 9.5% of American adults.