The term confidence level refers to: (a) the sum of an estimator's squared bias plus its variance, which indicates the degree to which it is consistent, efficient, and unbiased (b) the range of values among which an unknown population parameter can presumably be found (c) the percentage of interval estimates that can be expected to contain the actual value of the parameter being estimated when the same procedure of interval construction is used again and again (d) the sum of an estimator's squared bias plus the population mean (e) None of the above
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What does the term confidence level refer to?
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- Part 1 of 3 A researcher was investigating the size of math departments in Texas colleges. She believed the population standard deviation was 1.9. A sample of 42 colleges found their mean was 12.5. Find the 3-decimal small value of the 95% confidence interval of the mean. Part 2 of 3: Find the 3-decimal large value of the 95% confidence interval of the mean. Part 3 of 3: Find the 3-decimal margin of errorIn order to be able to statistically determine which levels of the significant main effect(s) differ dec the analysis of variance, which of the following is performed? A)t-test B)Simple linear regression analysis C)Post-hoc analysis D)Analysis of residuesSuppose that the height of Asian males aged 35-44 in the United States is normally distributed with a standard deviation of 3 in. Jeremy takes a simple random sample of 16 such men and notices that none of them are unusually tall or unusually short. He then calculates the average of the sample to be 67 in. and is planning on using this to find a 90% z-confidence interval for the true mean height. Can Jeremy use this information to find the z-confidence interval? Complete the following sentences. The population distribution is and the population standard deviation is Therefore, the sample to find a 90% z-confidence interval.
- A researcher is interested in studying the use of hypnosis to relieve pain. She took a random sample of 16 subjects and measured their sensory ratings. The mean of the sensory ratings was found to be 7.5 and standard deviation to be 2.3. It is known that the sensory ratings are normally distributed. Construct a 99% confidence interval for the mean sensory ratings of the population. a) (5.81, 9.19) b) (6.27, 8.73) c) (6.36, 8.64) d) (6.02, 8.98)a) which for these data is 32.1470, 42.3520, or 10.0674 c) that minimizes the error sum of squares, total sum of squares, or regression sum of squares…for which these data is 32.1470, 42.3520, or 10.0674The week before the bill to repeal Obamacare came up for consideration in the Senate, one polling agency increased the size of the random sample of U.S. adults they surveyed on this issue from 500 to 1500. What effect would this increase have on the polling agency's estimate of the proportion of U.S. adults in favor of repealing Obamacare, assuming the true proportion in favor remained constant? (A) A reduction in the variability of the estimate (B) An increase in the variability of the estimate (C) A reduction in the bias of the estimate (D) An increase in the bias of the estimate (E) A reduction in both the variability and the bias of the estimate
- In a research setting, the efficiency of homecare workers (part-time and full-time) were compared. Data is given below. Is there a difference between full-time and part-time homecare workers? (Variances are assumed to be homogenous, α=0.05). Group Efficiency Points Group Efficiency Points Full-time 5 Part-time 1 Full-time 3 Part-time 3 Full-time 4 Part-time 4 Full-time 1 Part-time 4 Full-time 2 Part-time 2 Full-time 3 Part-time 0 Full-time 2A researcher intends to estimate the effect of a drug on the scores of human subjects performing a task of psychomotor coordination. The members of a random sample of 9 subjects were given the drug prior to testing. The mean score in this group was 9.07, and the sample variance was 17.68. An independent random sample of 10 subjects was used as a control group and given a placebo prior to testing. The mean score in this control group was 15.21, and the sample variance was 27.48. Assuming that the population distributions are normal with equal variances, find a 90% confidence interval for the difference between the population mean scores The confidence interval is<, -,O (Round to two decimal places as needed.)The student will conduct a test of a single variance. Suppose an airline claims that its flights are consistently on time with an average delay of at most 15 minutes. It claims that the average delay is so consistent that the variance is no more than 150 minutes. Doubting the consistency part of the claim, a disgruntled traveler calculates the delays for his next 25 flights. The average delay for those 25 flights is 22 minutes with a standard deviation of 15 minutes. A sample standard deviation of 15 minutes is the same as a sample variance of ["", ""] minutes. find the a. Degrees of freedom = ["", ""] b. Chi2 test statistic = ["", ""] c. p-value =
- The electric cooperative needs to know the mean household usage of electricity by its non-commercial customers in kWh per day. They would like the estimate to have a maximum error of 0.14 kWh. A previous study found that for an average family the variance is 4.84 kWh and the mean is 19.1 kWh per day. If they are using a 80% level of confidence, how large of a sample is required to estimate the mean usage of electricity? Question 8 options: 45 households 1959 households 949 housholds 405 householdsConsider the following 29 years worth of observed annual rainfall data (in inches) for a certain weather station shown. Treat the data as samples only. (Note: The data are arranged in chronological manner.) 43.30 53.02 63.52 45.93 48.26 50.51 49.57 43.93 46.77 59.12 54.49 47.38 40.78 45.05 50.37 54.91 51.28 40.01 53.29 67.59 58.71 42.96 55.77 41.31 58.83 48.21 44.67 67.72 43.11 (a) Make a time-series line graph showing the trend of observed rainfall data through time. (For year, just denote it as Year 1, Year 2 etc.). Draw the line graph by hand. (b) Make a grouped data representing the given rainfall data. Use the following class intervals: 40<=X<45, 45<=X<50, 50<=X<55, 55<=X<60, 60<=X<65, and 65<=X<70.Dr. Sylvester Stallone is a circadian rhythms researcher and believes sleep affects memory. Having collected data on a large number of subjects who are getting the recommended amount of sleep, he knows the mean digit span of this population is 5.6 digits. To test his hypothesis, he measures the digit span of 15 volunteers randomly selected from the population, after depriving them of one night’s sleep. The results show a mean (X bar) of 4.1 and a standard deviation of (s) 1.4. a. What does Dr. Stallone conclude, using and alpha of 0.05 (two tailed)? b. If appropriate, calculate the size of effect and provide an interpretation of the value?