In: Statistics and Probability
A renters' organization claims that the median number of rooms in renter-occupied units is
five.You randomly select 40renter-occupied units and obtain the results shown below. At
alphα=0.02, complete parts (a) through (f).
Unit Size | Number of units |
Fewer than 5 rooms | 12 |
5 rooms | 11 |
More than 5 rooms | 17 |
a. The claim is
b. What are Ho and Ha?
c. crticial value
d. test stat
e.Decide whether to reject or fail to reject the null hypothesis.
f. At the
2 %2%
significance level,
▼
there is not
there is
enough evidence to reject the organization's claim "The median number of rooms in renter-occupied units is
fivefive."
(a) claim is the median number of rooms in renter-occupied units is 5
(b)
alternative hypothesis, H0: the median number of rooms is 8.
alternative hypothesis is Ha: the median number if rooms is not 8
To run the test:
Step 1: Assign a value of 0 to those with rooms below your
hypothesized median, and 1, to those above.
so we get 17
Step 2: Find the obtained frequency (of). There are 12 below the
median (the median is 5), and 17 above.
of = 17 and 12
Step 3: Find the expected frequency (ef). The total number of
data point is 40 if 5 was a true median, we’d expect to have 20
rooms having below and 20 above
ef = 20
Step 4: Calculate the chi-square:
Χ2 = Σ [(of – ef)2/ef].
This is:
(17– 5)2/5+ (12 – 5)2/5
or 38.6
Step 5: Find the degrees of freedom. There are two observed frequencies (equal to two cells in a contingency table), so there is just one degree of freedom.
Step 6: Use a Chi-squared table to find the critical chi-square
value
for 1 degree of freedom and an alpha level of 0.02 (α = 0.02). This
equals 57.96
Since our Χ2 value is less than the critical Χ2 value,we fail to reject the null hypothesis (i.e. we can keep it) —that the median is 5. If the Χ2 value we calculated from our data had been more than the critical Χ2 value, we would be able to reject the null hypothesis and postulated median age of 5
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