The article “Automatic Filtering of Outliers in RR Intervals Before Analysis of Heart Rate Variability in Holter Recordings: a Comparison with Carefully Edited Data” (M. Karlsson, et al., Biomedical Engineering Online, 2012) reports measurements of the total power, on the log scale, of the heart rate variability, in the frequency
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Statistics for Engineers and Scientists
- What does the y -intercept on the graph of a logistic equation correspond to for a population modeled by that equation?arrow_forwardIn a study by Dr. Harold J. Morowitz of Yale University, data were gathered that showed the relationship between the death rate of men and the average number of hours per day that the men slept. These data are listed in the following table:arrow_forwardDioxin Researchers have linked an increase in the inci-dence of breast cancer in Italy to dioxin released by an industrial accident in 1976. The study identified 981women who lived near the site of the accident and were under age 40 at the time. Fifteen of the women had devel-oped breast cancer at an unusually young average age of 45. Medical records showed that they had heightened con-centrations of dioxin in their blood and that each tenfold increase in dioxin level was associated with a doubling ofthe risk of breast cancer. (Science News, Aug. 3, 2002)arrow_forward
- In this question we look at the relation between the logarithm of weakly earnings and years of education. Using data from the national longitudinal study of youth, we find the following results for a regression of log weekly earnings and years of education, experience, experience squared and an intercept: Log (earnings) = 4.016 + 0.092 . educi + 0.079 .expei + 0.002 . experi 2 ( 0.222) ( 0.008) ( 0.025) (0.001) a).Construct a 95% confidence interval for the effect of years of education on log weakly earnings b).Consider an individual with 10 year of experience. What would you expect to be the return to an additional year of experience for such an individual (the effect on log weakly earnings)?arrow_forwardKarr and Coats studied the effects of several chemicals on the growth of the German cockroach. the following table gives their data for the percent of the chemical ?-terpineol in the diet of 20% ?-terpineol. Percent ?-terpineol 1 10 25 Days to Adult Stage 129 113 115 A. On the basis of the data given in the table, find the best-fitting logarithmic function using least squares. State the square of the correlation coefficient. (Use 4 decimal places in your answer.)y(x) = r2 = B. Use this model to estimate the days to adult stage with a diet of 20% ?-terpineol. (Round to the nearest day.)When a 20% ?-terpineol, then there are days to adult stage.arrow_forwardA manufacturer claims that the tensile strength of a certain composite (in MPa) has the lognormal distribution with μ = 5 and σ = 0.5. Let X be the strength of a randomly sampled specimen of this composite. a) If the claim is true, what is P(X < 20)? b) Based on the answer to part (a), if the claim is true, would a strength of 20 MPa be unusually small? c) If you observed a tensile strength of 20 MPa, would this be convincing evidence that the claim is false? Explain. d) If the claim is true, what is P(X < 130)? e) Based on the answer to part (d), if the claim is true, would a strength of 130 MPa be unusually small? f) If you observed a tensile strength of 130 MPa, would this be convincing evidence that the claim is false? Explain.arrow_forward
- Recent publications have addressed the growing concern in the scientific community around the increased prevalence of CAT scans in children between the ages of 7-18 and the growing rate of childhood cancers. Suppose the researcher plans to gather a SRS from a group of children in this age range who have received one or more CAT scans, and a SRS from a group of children who have never received a CAT scan and compare the number of cases of childhood cancers that develop over a prolonged period of time. Assume the following table summarizes the descriptive statistics for his samples. Population Average cases of childhood cancers Standard deviaton Sample size >CAT scan 24.6 2.4 1,894 No CAT scans 11.4 1.9 2,745 A) Carry out the appropriate statistical test to answer the researcher’s hypothesis regarding the difference in average cases of childhood cancers in children aged 7-18 receiving one or more CAT scans versus those that have never received a CAT scan. Use an alpha level…arrow_forwardIn a recent survey, ice cream truck drivers in Cincinnati, Ohio, reported that they make about $280 in income on a typical summer day. The income was generally higher on days with longer work hours, particularly hot days, and on holidays. The accompanying data file includes five weeks of the driver’s daily income (Income), number of hours on the road (Hours), whether it was a particularly hot day (Hot = 1 if the high temperature was above 85°F, 0 otherwise), and whether it was a Holiday (Holiday = 1, 0 otherwise). Income Hours Hot Holiday 196 5 1 0 282 8 0 0 318 6 1 0 232 5 1 0 276 8 0 0 312 8 0 1 193 5 0 1 110 4 0 0 321 8 1 0 283 8 0 0 325 8 1 0 247 7 0 1 398 8 1 1 448 8 1 1 214 4 0 0 235 8 0 0 238 8 0 0 148 3 1 0 313 8 0 1 449 8 1 1 332 8 1 1 247 8 0 0 363 7 1 0 393 7 1 1 254 8 0 0 228 8 0 0 355 6 1 1 248 7 0 1 291 8 1 0 255 5 1 0 239 6 0 0 181 6 0 0 222 7 0 0 170 5 0 1 374 6 1 1 1. Estimate the effect of…arrow_forwardHow sensitive to changes in water temperature are coral reefs? To find out, scientists examined data on sea surface temperatures, in degrees Celsius, and mean coral growth, in centimeters per year, over a several‑year period at locations in the Gulf of Mexico and the Caribbean Sea. The table shows the data for the Gulf of Mexico. Sea surface temperature 26.726.7 26.626.6 26.626.6 26.526.5 26.326.3 26.126.1 Growth 0.850.85 0.850.85 0.790.79 0.860.86 0.890.89 0.920.92 (b) Find the correlation ?r step by step. Round off to two decimals places in each step. First, find the mean and standard deviation of each variable. Then, find the six standardized values for each variable. Finally, use the formula for ?r . Round your answer to three decimal places.arrow_forward
- The operator of a pumping station has observed that demand for water during early afternoon hours has an approximately exponential distribution with mean 100 cfs (cubic feet per second).a) Find the probability that the demand will exceed 200 cfs during the early afternoon on arandomly selected day.b) What water-pumping capacity should the station maintain during early afternoons sothat the probability that demand will exceed capacity on a randomly selected day isonly .01?arrow_forwardQUESTION 11 Historically, the proportion of people who trade in their old car to a car dealer when purchasing a new car is 48%. Over the previous 6 months, in a sample of 115 new-car buyers, 46 have traded in their old car. To determine (at the 10% level of significance) whether the proportion of new-car buyers that trade in their old car has statistically significantly decreased; what is the critical value? (please round your answer to 2 decimal places)arrow_forwardA group of six, obese adult men had their weights recorded both before and 10 months after having a diet treatment to help manage their weight. Observe the information presented in the table below: The weights of six obese adult men both before and 10-months after having a diet treatment Before Diet Treatment After Diet Treatment 250 240 225 215 220 198 311 300 326 298 205 205 Test at α = 0.05 the hypothesis that for the group, there was a statistically significant average decrease in weight from before diet treatment to 10 months after. Hint: This is hypothesis testing for paired samples. Here, you will use a paired t test.arrow_forward
- Algebra & Trigonometry with Analytic GeometryAlgebraISBN:9781133382119Author:SwokowskiPublisher:CengageGlencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw Hill