Hypothesis Test for a Population Proportion

Many investors and financial analysts believe the Dow Jones Industrial Average (DJIA) gives a good barometer of the overall stock market. On January 31, 2006, 9 of the 30 stocks making up the DJIA increased in price (The Wall Street Journal, February 1, 2006). On the basis of this fact, a financial analyst claims we can assume that 30% of the stocks traded on the New York Stock Exchange (NYSE) went up the same day.

A sample of 50 stocks traded on the NYSE that day showed that 21 went up.

You are conducting a study to see if the proportion of stocks that went up is is significantly more than 0.3. You use a significance level of α=0.10α0.10.

What is the test statistic for this sample? (Report answer accurate to three decimal places.) 

z = 

What is the p-value for this sample? (Report answer accurate to three decimal places.) 

P-value = 

The p-value is...

• less than (or equal to) αα
• greater than αα

This test statistic leads to a decision to...

• reject the null hypothesis
• accept the null hypothesis
• fail to reject the null hypothesis

As such, the final conclusion is that...

• There is sufficient evidence to warrant rejection of the claim that the proportion of stocks that went up is is more than 0.3.
• There is not sufficient evidence to warrant rejection of the claim that the proportion of stocks that went up is is more than 0.3.
• The sample data support the claim that the proportion of stocks that went up is is more than 0.3.
• There is not sufficient evidence to support the claim that the proportion of stocks that went up is is more than 0.3.