Is there a relationship between confidence intervals and two-tailed hypothesis tests? Let c be the level of confidence used to construct a confidence interval from sample data. Let ? be the level of significance for a two-tailed hypothesis test. The following statement applies to hypothesis tests of the
(A corresponding relationship between confidence intervals and two-tailed hypothesis tests also is valid for other parameters, such as p, μ1 − μ2, or p1 − p2, which we will study in later sections.) Whenever the value of k given in the null hypothesis falls outside the c = 1 – α confidence interval for the parameter, we reject H0. For example, consider a two-tailed hypothesis test with ? = 0.01 and
H1: μ ≠ 21
A random sample of size 20 has a sample mean x = 19 from a population with standard deviation σ = 7.
(b) Using methods of Chapter 8, find the P-value for the hypothesis test. (Round your answer to four decimal places.)
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- Match each of the hypothesis test conclusions below to the corresponding p-value. There is not enough evidence to reject the null hypothesis at any reasonable significance level. The evidence against the null and in favor of the alternative hypothesis is extremely strong. The evidence against the null hypothesis is statistically significant at the 10% level, but not at the 5% level. The result is statistically significant at the 5% level but not at the 1% level. I. p-value = .0003 II. p-value = .317 III. p-value = .089 IV. p-value = .039arrow_forwardWhich of the following is not true when using the confidence interval method for testing a claim about u when a is unknown? Choose the correct answer below. OA. The P-value method, the traditional method, and the confidence interval method are equivalent and yield the same results. OB. For a one-tailed hypothesis test with a 0.05 significance level, one must construct a 90% confidence interval. OC. The P-value method and the classical method are not equivalent to the confidence interval method in that they may yield different results. OD. For a two-tailed hypothesis test with a 0.05 significance level, one must construct a 95% confidence interval.arrow_forwardYou're running a one-sample t-test comparing your sample (? = 27.9, ?? = 3.8) of 28 observations with a population that has μ = 36.7 at ? = 0.05. Calculate ?_???_____ , your confidence interval:______ to_______ , and your decision regarding the null hypothesis (reject/fail to reject)______ t_obs: ___ Confidence Interval: ___ to ___ Reject or fail to reject: _____arrow_forward
- The mean coffee consumption of a population of nurses is 9 cups of coffee per week. A group of 10 ICU nurses consume a mean of 13 cups of coffee per week, where the estimated standard error of the mean is 1.90. What is the 95% confidence interval for this sample and should we retain or reject the null hypothesis (H0), applying an alpha level of 0.05? 9.28 to 16.72; retain H0 8.76 to 17.24; retain H0 8.70 to 17.30; retain H0 4.70 to 13.30; reject H0arrow_forwardTonya wants to estimate what proportion of her school's seniors plan to attend the prom. She interviews an SRS of 50 of the 750 seniors in her school and finds that 36 plan to go to the prom. Which of the following is not one of the conditions that needs to be met in order to construct a confidence interval for the parameter? Large Counts: n(1 – p) = 14 10 Random: The sample is a simple random sample 10% n = 50 is less than 10% of the population size Large Counts: nộ = 36 > 10 Normal/Large Sample: The sample size is large n 50 30. O O O O Oarrow_forwardSuppose we are making predictions of the dependent variable y for specific values of the independent variable x using a simple linear regression model holding the confidence level constant. Let Width (C.I) = the width of the confidence interval for the average value y for a given value of x, and Width (P.I) = the width of the prediction interval for a single value y for a given value of x. Which of the following statements is true? Width (C.I) = 0.5 Width (P.I) Width (C.I) = Width (P.I) Width (C.I) > Width (P.I) Width (C.I) < Width (P.I)arrow_forward
- Looking at youth depression scores from a general sample of random children in the US, we want to determine if our sample is significantly different than the national average of scores of children with depression in the US. The national average of scores on a measure of depression is 5 points. We have no reason to assume it will be higher or lower than the US national average. The sample: 11 9 12 3 3 4 13 1. What is the null and alternative hypotheses? Do not specify any directionality. 2. What did you discover (using 95% Cl)? Provide an interpretation.arrow_forwardConsider the following two confidence intervals for B₁: 90% confidence interval: [0.49, 29.51] 95% confidence interval: [-2.29, 32.29] You want to test the null hypothesis that B₁ = 0 against the alternative hypothesis that ß₁ ‡ 0. Which of the following is true? Select all that apply. You reject the null hypothesis at the 5% significance level You fail to reject the null hypothesis at the 10% significance level. You fail to reject the null hypothesis at the 5% significance level You reject the null hypothesis at the 10% significance levelarrow_forwardDetermine whether the following statements are True or False: In a confidence interval (CI) for a population mean, the margin of error (MOE) is half the width of the CI. If we constructed 1000 independent 90% CI’s for a population mean µ, thenwe’d expect about 900 of them to contain µ If we increase the sample size of SRS’s, then the width of the CI’s corresponding to the SRS’s decreases, i.e., the CI’s become narrowerarrow_forward
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