Earlier we discussed about the Hypothesis Testing , what is one sample and two sample tests. Also we have gone through one sample t and z test.

Here we are going to discuss p value and one sample p test.

What is p value ?

  • p value is the lowest value of alpha for which the null hypothesis can be rejected.
  • If p is lesser than alpha(usually it is .05), “reject the null hypothesis”.
  • If p is higher than the alpha, “failed to reject the null hypothesis”.

Let’s say p=.001,null hypothesis is rejected.

Hope we are clear about the p value. Now let’s talk about one sample p test.

One Sample p test :

We calculate the z statistics only for the test.
Null Hypothesis: p=p0

Below is the formula to calculate the z statistics when percentage or proportion are given.

One Sample p test

Let’s understand the test by solving one of the problem.

Problem – There is a town name ABC , where smoking rate as per the past data is 20% . Currently there are 100 samples are picked from the town and found 15 as smoker. Has the smoking rate changed?(95% confidence interval).

H0 =.20 ,Ha ≠.20
p0=.20 ,p=.15,n=100

Zcalc=(0.15-0.20)/(sqrt((.20*.80)/100))=-1.25
Zcritical=-1.96

Zcal is less than Zcritical , means failed to reject the null hypothesis. It means smoking rate is as same as past smoking rate 20%.

Let’s solve one problem related to smoking rate only.

Problem – There is a town name ABC , where smoking rate as per the past data is 20% Currently there are 100 samples are picked from the town and found 15 as smoker. Has the smoking rate reduced?(95% confidence interval).

H0>=.20 ,Ha <.20
p0=.20 ,p=.15,n=100

Zcalc=(0.15-0.20)/(sqrt((.20*.80)/100))=-1.25
Zcritical=-1.645

Zcal is less than Zcritical , means failed to reject the null hypothesis again.


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