Posted by **Mary** on Tuesday, March 30, 2010 at 12:28am.

Inferences about Two Proportions technique (Chapter 9):

There is a claim that proportion of successes increased in 2009 compare to 2008.

For data given in Table 1

Table 1

Number of cases Number of successes

2008 400 180

2009 500 235

Calculate pooled sample proportion and z-test statistics

Use a significance level of á = 0.05 to make decision if there is a considerable change of proportion of successes.

- STATS -
**MathGuru**, Tuesday, March 30, 2010 at 7:41pm
This would fit a one-tailed proportional z-test (using proportions). The test would be one-tailed because of the alternate hypothesis (p2009 > p2008).

Here is one formula:

z = (p2009 - p2008)/√[pq(1/n1 + 1/n2)]

...where 'n' is the sample sizes, 'p' is (x1 + x2)/(n1 + n2), and 'q' is 1-p.

I'll get you started:

p = (180 + 235)/(400 + 500) = ? -->once you have the fraction, convert to a decimal (decimals are easier to use in the formula).

q = 1 - p

p2008 = 180/400

p2009 = 235/500

Convert all fractions to decimals. Plug those decimal values into the formula and find z. Once you have this value, compare to the critical value from a z-table using 0.05 significance for a one-tailed test.

If the test statistic exceeds the critical value from the table, reject the null and accept the alternate hypothesis (p2009 < p2008). If the test statistic does not exceed the critical value from the table, then you cannot reject the null and you cannot conclude a difference.

I hope this will help.

## Answer This Question

## Related Questions

- Math - 1. The table shows the growth in the number of Mcdonalds restaurants ...
- AP Statistics - 12) Which of the following statements is true? a) The sampling ...
- stats 3 - 2. Collect the data pertaining to the number of customers serviced (by...
- Statistic - TABLE 12-3 A computer used by a 24-hour banking service is supposed ...
- Math - A surgical technique is performed on 7 patients. There is a 70% chance of...
- STATS - 7. Calculate b0 and b1 and make an equation of regression line for the ...
- comprehension:make inferences - make inferences about the situations or ...
- stats - 7. Calculate b0 and b1 and make an equation of regression line for the ...
- Math - For a binomial distribution with n=20 trials and probability of success p...
- statistics - I have just a couple questions I have trouble understanding... can ...

More Related Questions