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Some computer output for an analysis of variance test to compare means is given.

a) How many groups are there?
b) State the null and alternative hypotheses.
c) What is the p-value?
d) Give the conclusion of the test, using a 5% significance level.

Source DF SS MS F
Group s 4 1200.0 300.0 5.71
Error 35 1837.5 52.5
Total 39 3037-5

User Pcent
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1 Answer

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Final answer:

You're inquiring about an ANOVA test, which determines if there are differences among group means. The provided output indicates there are 5 groups, and we're testing the null hypothesis that all group means are equal against the alternative that at least one differs. We need the p-value to conclude, often found using statistical software.

Step-by-step explanation:

The question you're asking is about an Analysis of Variance (ANOVA) test, which is used to compare the means of different groups. Here are the detailed explanations to your questions:

• a) How many groups are there? There are 5 groups indicated by the degrees of freedom (DF) of the group, which is 4. As degrees of freedom are calculated as the number of groups minus one, there must be 5 groups.

• b) State the null and alternative hypotheses. The null hypothesis (H0) is that all group means are equal. The alternative hypothesis (Ha) is that at least one group mean is different from the others.

• c) What is the p-value? The p-value is not provided directly in the given output. However, with an F statistic of 5.71 and degrees of freedom for the group (4) and error (35), you can determine the p-value using an F distribution table or software that provides ANOVA capabilities.

• d) Give the conclusion of the test, using a 5% significance level. Given a typical ANOVA analysis, if the p-value is less than the significance level (α = 0.05), we reject the null hypothesis. Without the exact p-value, we cannot provide a definitive conclusion, but generally, a higher F statistic (such as 5.71) indicates a lower p-value, which suggests that it's likely we would reject the null hypothesis, concluding that there is a statistically significant difference between the group means. Without the exact p-value, we would mention the correct option in the final part of the analysis after determining the p-value using appropriate statistical software or an F distribution table.

User Senthil
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