Concept explainers
Refer to Exercise 8.88. Another common insecticide, diazinon, yielded LC50 measurements in three experiments of 7.8, 1.6, and 1.3.
- a Estimate the
mean LC50 for diazinon, with a 90% confidence interval. - b Estimate the difference between the mean LC50 for DDT and that for diazinon, with a 90% confidence interval. What assumptions are necessary for the method that you used to be valid?
8.88 The Environmental Protection Agency (EPA) has collected data on LC50 measurements (concentrations that kill 50% of test animals) for certain chemicals likely to be found in freshwater rivers and lakes. (See Exercise 7.13 for additional details.) For certain species of fish, the LC50 measurements (in parts per million) for DDT in 12 experiments were as follows:
Estimate the true mean LC50 for DDT with confidence coefficient .90. Assume that the LC50 measurements have an approximately
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Mathematical Statistics with Applications
- Rangecient of Variaice: 45.31N 6.- The day after Thanksgiving-called Black Friday–is one of the largest shopping days in the United States. A group of researchers conducted interviews with a sample of 38 women shopping on Black Friday to gauge their shopping habits and reported the results in a published paper, in 2011. One question was, "“How many hours do you usually spend shopping on Black Friday?" Data for the 38 shoppers are listed here: 66443 16 4 4 5 6 6 5 5 4 6 5 6 4 5 4 44 7 12 5 86 10 5 8 8 3 38 5 6 10 11. Descriptive statistics for these data are in this table: AExplore Data - Descriptive Statistics Options Which column of data would you like to explore? Summary statistics: Explore Data - Column 4 Variance Std. dev. Std. err. . Median Range Min Max Q1 Q3 Column n Mean Sample Size, ni 38 6.078947 38 6 0789474 7 5881935 2.7546676 044686609 13 3 16 4 7 var4 Meani Nedi an: Midrange: 9.5 6.658987 7.588193 Standard Deviation, s I 2.754668 Mean Absolute Deviation 1.958449 Variance,…arrow_forwardSuppose you will perform a test to determine whether there is sufficient evidence to support a claim of a linear correlation between two variables. Find the critical values of r given the number of pairs of data n and the significance level α. n = 19, α = 0.05 Group of answer choices r = ±0.575 r = 0.468 r = 0.456 r = ±0.456arrow_forwardthank you…arrow_forward
- A researcher wants to evaluate the effectiveness of a patch he thinks will significantly decrease lower back pain. Prior to testing, each of n = 8 patients rated their current level of back pain. After wearing the patch for 90 minutes, a second rating is recorded. The data show a mean difference of MD= -4 and SS =56. Do the results indicate a significant decrease? Use α = .01. 1. hypotheses? 2. What is the critical value? 3. What is the calculated test statistic? 4. What is your conclusion and interpretation? 5. What percent of the decrease is actually due to the pain relief patch?arrow_forwardUse the following information from a multiple regression analysis. n=15 b1=2 b2=6 Sb1=1.4 Sb2=0.5 a. Which variable has the largest slope, in units of a t statistic? b. Construct a 90% confidence interval estimate of the population slope, β1. c. At the 0.10 level of significance, determine whether each independent variable makes a significant contribution to the regression model. On the basis of these results, indicate the independent variables to include in this model.arrow_forwardAnswer part a and barrow_forward
- Here are the scatter plots for two sets of bivariate data with the same response variable. The first compares the variables x & y. The second compares the variables w & y 098 Which explanatory variable has a stronger relationship with the response variable y? O The first variable (x) has a stronger relationship with the response variable y. O The second variable (w) has a stronger relationship with the response variable y.arrow_forwardFor the data and sample regression equation shown below, do the following. a. Decide, at the 5% significance level, whether the data provide sufficient evidence to conclude that x is useful for predicting y. b. Find a 95% confidence interval for the slope of the population regression line. 23 10 3 0 -4 2 y=-3+1.2x, x₁ = 10, x² = 30, b₁ = 1.2, and se = 3.0659 X y 4 1 a. What are the hypotheses for the test? O A. Ho: B₁ = 0 and H₂: B₁ #0 OB. Ho: B₁ = 0 and H₂: B₁ >0 OC. Ho: B₁ = 0 and H₂: B₁ <0 O D. Ho: B₁ #0 and H₂: B₁ = 0 What is the test statistic? (Round to two decimal places as needed.) Find the P-value. P-value= (Round to three decimal places as needed.)arrow_forwardHotel prices worldwide are projected to increase by 3% next year (Lodging Magazine website, June 15, 2016), but is there a difference between Europe and the U.S.? Suppose we have projected changes in hotel costs for 47 randomly selected major European cities and 53 randomly selected major U.S. cities. These data are provided in the DATAfile IntHotels. Use α= .01 What is the p-value?.What is your conclusion?arrow_forward
- 10.2.23 Find the regression equation, letting overhead width be the predictor (x) variable. Find the best predicted weight of a seal if the overhead width measured from a photograph is 1.9 cm. Can the prediction be correct? What is wrong with predicting the weight in this case? Use a significance level of 0.05. Overhead Width (cm) Weight (kg) 9.4 8.3 7.5 - X 8.2 7.3 9.7 i Critical Values of the Pearson Correlation Coefficient r 195 184 287 246 220 190 Click the icon to view the critical values of the Pearson correlation coefficient r Critical Values of the Pearson Correlation Coefficient r k-0.05 0.950 0.878 0.811 0.754 0.707 0.666 0.632 0.602 0.576 0.553 0.532 0.514 0 497 0.482 0.468 0.456 10.444 The regression equation is y =+x. (Round to one decimal place as needed.) a-0.01 NOTE: To test H: p=0 against H,: p+0, reject H, if the absolute value of in 0.990 0.959 0.917 0.875 0.834 0.798 0.765 0.735 0.708 0.684 0.661 0.641 0.623 0.606 0.590 0.575 0.561 4 16 r is greater than the…arrow_forwardStandard Error is a measure of how much the point estimate changes from sample to sample. The proportion of heads from flipping five coins has a relatively large standard error (SE = .2236), and it is not uncommon to see point estimates from 0% to 100%. The proportion of heads from flipping 1000 coins has a relatively small standard error (SE = .0158), and points estimates will rarely fall outside 45% to 55% heads. Р(1 — р) For proportions, the formula is SE = where n is the sample size and p = p, the sample n proportion (point estimate). Compute the standard error, given a) point estimate = 0.61, null value = 0.7, and n = 120. The standard error = b) point estimate = 0.42, null value = 0.5, and n = 50. The standard error =arrow_forwardThe price X (dollars per pound) and consumption y (in pounds per capita) of beef were samples for 10 randomly selected years. The following data should be used to answer the question that follows. n = 10 Ex = 36.19 Ex² = 134.17 2.9 < x < 6.2 Ey = 774.7 Iy? = 60739.23 Exy = 2832.21 %3D Using this data, a student calculated SSy = 28.43 SSx = 3.2 SSyy = 717. Which one of %3D the following represents the equation of the regression line between price and consumption O y-hat = 25.22x -13.8 O y-hat = 25.22x +13.8 O y-hat 8.88x + 453.37 O y-hat = 8.88x +45.34arrow_forward
- Glencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw Hill