Chapter 10 Statistical Inference About Means and Proportions with Two Populations Learning Objectives 1. Be able to develop interval estimates and conduct hypothesis tests about the difference between two population means whenandare known. 2. Know the properties of the sampling distribution of . 3. Be able to use the t distribution to conduct statistical inferences about the difference between two population means whenandare unknown. 4. Learn how to analyze the difference between two population means when the samples are independent and when the samples are matched. 5. Be able to develop interval estimates and conduct hypothesis tests about the difference between two population proportions. 6. Know the properties of the sampling …show more content…
Penney. 9. a. = 22.5 - 20.1 = 2.4 b. Use df = 45. c. t.025 = 2.014 d. 2.4 2.1 (.3 to 4.5) 10. a. b. Use df = 65 c. Using t table, area in tail is between .01 and .025 two-tail p-value is between .02 and .05. Exact p-value corresponding to t = 2.18 is .0329 d. p-value .05, reject H0. 11. a. b. c. = 9 - 7 = 2 d. Use df = 9, t.05 = 1.833 2 2.17 (-.17 to 4.17) 12. a. = 22.5 - 18.6 = 3.9 b. Use df = 87, t.025 = 1.988 3.9 (.6 to 7.2) 13. a. b. = 9.3 - 4.2 = 5.1 tons Memphis is the higher volume airport and handled an average of 5.1 tons per day more than Louisville. Memphis handles more than twice the volume of Louisville. c. Use df = 17, t.025 = 2.110 5.1 1.82 (3.28 to 6.92) 14. a. H0: Ha: b. c. = 87.55 Rounding down, we will use a t distribution with 87 degrees of freedom. From the t table we see that t = -2.41 corresponds to a p-value between .005 and .01. Exact p-value corresponding to t = -2.41 is .009. d. p-value .05, reject H0. We conclude that the salaries of staff nurses are lower in Tampa than in Dallas. 15. 1 for 2001 season 2 for 1992 season H0: Ha: b. = 60 - 51 = 9 days 9/51(100) = 17.6% increase in number of days. c. Using t table, p-value is between .005 and .01. Exact p-value corresponding to t = 2.48 is .0076 p-value .01,
We can also test if there is a significant difference between the average height for females and the average height for the males.
Inferential statistics helps us to analyze predictions, inferences, or samples about a specific population from the observations that they make. “With inferential statistics, you are trying to reach conclusions that extend beyond the immediate data alone” (Trochim, 2006). The goal for this type of data is to review the sample data to be able to infer what the test group may think. It does this by making judgment of the chance that a difference that is observed between the groups is indeed one that can be counted on that could have otherwise happened by coincidence. In order to help solve the issue of generalization, tests of significance are used. For example, a chi-square test or T-test provides a person with the probability that the analysis’ sample results may or may not represent the respective population. In other words, the tests of significance provides us the likelihood of how the analysis results might have happened by chance in a scenario that a relationship may not exist between the variables in regards to the population that is being studied.
2) Compute the standard deviation for each of the four samples. Does the assumption of .21 for the population standard deviation appear reasonable?
• Provide at least two examples or problem situations in which statistics was used or could be used.
Because the p-value of .035 is less than the significance level of .05, I will reject the null hypothesis at 5% level.
Topics Distribution of the sample mean. Central Limit Theorem. Confidence intervals for a population mean. Confidence intervals for a population proportion. Sample size for a given confidence level and margin of error (proportions). Poll articles. Hypotheses tests for a mean, and differences in means (independent and paired samples). Sample size and power of a test. Type I and Type II errors. You will be given a table of normal probabilities. You may wish to be familiar with the follow formulae and their application.
If the total sample size is over 15, two sample t tests are safe if there are no
Explain how the data collected will provide the data necessary to support or negate the hypothesis or proposition
The t-test is a parametric analysis technique used to determine significant differences between the scores obtained from two groups. The t-test uses the standard deviation to estimate the standard error of the sampling distribution and examines the differences between the means of the two groups. Since the t-test is considered fairly easy to calculate, researchers often use it in determining differences between two groups. When interpreting the results of t-tests, the larger the calculated t ratio, in absolute value, the greater the difference between the two groups. The significance of a t ratio can be determined by comparison with the critical values in a
“Hypothesis testing is a decision-making process for evaluating claims about a population” (Bluman, 2013, p. 398). This process is used to determine if you will accept or reject the hypothesis. The claim is that the bottles contain less than 16 ounces. The null hypothesis is the soda bottles contain 16 ounces. The alternative hypothesis is the bottles contain less than 16 ounces. The significance level will be 0.05. The test method to be used is a t-score. The test statistic is calculated to be -11.24666539 and the P-value is 1.0. The P-value is the probability of observing a sample statistic as extreme as the test statistic, assuming the null hypothesis is true. The T Crit value is 1.69912702. The calculations show there is enough evidence to support the claim that the soda bottles do
At the .01 significance level is there a difference in the mean amount purchased on an impulse at the two stores? Explain these results to a person who knows about the t test for a single sample but is unfamiliar with the t test for independent means.
1. Discuss when it is appropriate to use the paired t-test and the Wilcoxon matched-pairs
Statistics show if the treatment has had a good number of responses to the treatment or a bad number of responses. Back in 1775 they
This paper will examine a data analysis and application for an independent t test comparing the mean GPAs of a sample of male and female students. It will pose a research question that the data will set out to answer. It will provide a null hypothesis and an alternative hypothesis, and will provide an analysis showing why the null hypothesis should be accepted or rejected in favor of the alternative hypothesis.
Since 3.27 the t statistic is in the rejection area to the right of =1.701, the level of