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I wanted to  look for a difference in the proportions of North Olmsted High School students who own an iPhone and North Olmsted High School students who own an Android, So I  chose to use a 2 proportion Z-test. I decided since the majority of high school students have an iPhone and/or Android I would test these two phones. I also included other in the possibility that a student may not have either of the two.


The Survey

What type of phone do you own?

(circle the option that applies)

  • Iphone


  • Android


  • Other


Study


Hypothesis Test 2 Prop Z Test(Difference Between Proportions)

1.p1 = the proportion of North Olmsted High School students who own an iPhone.

p2 = the proportion of North Olmsted High School students who own an Android.

2.    H0: P1 -  P2 =0

3.     Ha: P1 - P2≠0  

4.                α = 0.05

5. 

6. Assumptions

  • The Samples were independent and selected randomly.

  • Both of the samples are less than 10% of the population

  • np has to be greater than or equal to 10. np=50>10

7. Z= 5.22 at 68 df

8.p=0.000



Minitab Data


Test and CI for Two Proportions


Sample   X   N  Sample p

1       47  69  0.681159

2       19  69  0.275362



Difference = p (1) - p (2)

Estimate for difference:  0.405797

95% CI for difference:  (0.253481, 0.558113)

Test for difference = 0 (vs ≠ 0):  Z = 5.22  P-Value = 0.000


Fishers exact test: P-Value = 0.000

Graphs