Concept explainers
A research specialist for a large seafood company plans to investigate bacterial growth on oysters and mussels subjected to three different storage temperatures. Nine cold-storage units are available. She plans to use three storage units for each of the three temperatures. One package of oysters and one package of mussels will be stored in each of the storage units for 2 weeks. At the end of the storage period, the packages will be removed and the bacterial count made for two samples from each package. The treatment factors of interest are temperature (levels: 0, 5, 10°C) and seafood (levels: oysters, mussels). She will also record the bacterial count for each package prior to placing seafood in the cooler. Identify each of the following components of the experimental design.
- a. Factors
- b. Factor levels
- c. Blocks
- d. Experimental unit
- e. Measurement unit
- f. Replications
- g. Treatments
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Chapter 2 Solutions
An Introduction to Statistical Methods and Data Analysis
- A study conducted at the University of Denver investigated whether babies take longer to learn to crawl in cold months, when they are often bundled in clothes that restrict their movement, than in warmer months. Infants born during the study year were split into twelve groups, one for each birth month. We consider the average crawling age of babies in each group against the average temperature when the babies are six months old (that's when babies often begin trying to crawl). Temperature is measured in degrees Fahrenheit and age is measured in weeks. 34 33 32 31 30- 29 30 40 50 60 70 Temperature (F) a) Describe the relationship between temperature and crawling age. Choose all answers that apply. There is strong, negative, linear relationship between termperature and crawling age nThere is a somewhat moderate, negative, linear relationship between temperature and crawling age nThere is a moderate, positive, linear relationship between the temperature and crawling age The point at the…arrow_forwardDue to stress, many patients who undergo major elective surgery experience an increase in blood pressure before their scheduled operations. The ABC hospital has started a new yoga program intended to reduce stress and blood pressure. A random sample of 50 patients who know they must undergo a major elective surgery was enrolled in this program. The systolic blood pressure of each patient was measured prior to starting the yoga program. At the end of the yoga program, the systolic blood pressure of each patient was measured again. Question: What statistical test can be used to test if the yoga program is effective in reducing blood pressure?(choose one answer): The t-test for two independent samples C. The one-sample test for the binomial proportion The F-test for the equality of two variances The paired t-testarrow_forwardA 13-mile stretch rural highway meanders through a largely untrammeled section of northwestern South Dakota. The highway has a 10-year crash history which includes 2 fatal crashes, 3 major crashes, 6 minor crashes, 9 possible/unknown crashes, and 35 property damage only (PDO) crashes. 80% of the PDO crashes are animal-related, primarily deer. Total daily VMT has been calculated at 5.200 vehicle-miles-travelled with 400 vpd for the first 6 miles and 600 vpd for the next 3 miles. What is the AADT (in vpd) for the remaining miles?arrow_forward
- Arsenic is a naturally occurring chemical that can enter groundwater through eroding granite or from a burned forest. A health organization recommends drinking water should contain no more than 10 parts per billion (ppb) of arsenic. A company produces filters to clean arsenic from private wells that could be affected by the groundwater. The company wants to investigate the effectiveness of a new filter compared to that of an older filter. They will test the filters on a field that is bordered on one side by a granite ledge and on the other side by a burned forest. The field is divided into 88 square plots of equal size, and a well to collect groundwater is drilled in the center of each plot. One filter will be used in each well. The following diagram shows the placement of the wells in the field. The company will use four of each type of filter to conduct the investigation. A randomized block design will be used. (a) Assuming there is a difference in the effectiveness of the two…arrow_forwardA laboratory research group did a microarray experiment five years ago with 10 subjects in the normal group, and 6 subjects in the diet group; one microarray per subject. They never published their results because they felt like their diet group was too small. Now they have more money and they want to get 4 diet animals, and run 4 new microarrays on those animals. They plan to add that data to their study so they can increase their statistical discovery power, and finally publish their results. Although increasing the number of subjects should increase the statistical power of the study, give a reason why increasing the number of samples might NOT result in more significant results.arrow_forwardA farmer uses a lot of fertilizer to grow his crops. The farmer’s manager thinks fertilizer products from distributor A contain more of the nitrogen that his plants need than distributor B’s fertilizer does. He takes two independent samples of four batches of fertilizer from each distributor and measures the amount of nitrogen in each batch. Fertilizer from distributor A contained 23 pounds per batch and fertilizer from distributor B contained 18 pounds per batch. Suppose the population standard deviation for distributor A and distributor B is four pounds per batch and five pounds per batch, respectively. Assume the distribution of nitrogen in fertilizer is normally distributed. Let µ1 and µ2 represent the average amount of nitrogen per batch for fertilizers A and B, respectively. Which of the following is an appropriate p-value?arrow_forward
- A farmer uses a lot of fertilizer to grow his crops. The farmer’s manager thinks fertilizer products from distributor A contain more of the nitrogen that his plants need than distributor B’s fertilizer does. He takes two independent samples of four batches of fertilizer from each distributor and measures the amount of nitrogen in each batch. Fertilizer from distributor A contained 23 pounds per batch and fertilizer from distributor B contained 18 pounds per batch. Suppose the population standard deviation for distributor A and distributor B is four pounds per batch and five pounds per batch, respectively. Assume the distribution of nitrogen in fertilizer is normally distributed. Let µ1 and µ2 represent the average amount of nitrogen per batch for fertilizers A and B, respectively. Which of the following is the appropriate conclusion at the 5% significance level?arrow_forwardA farmer uses a lot of fertilizer to grow his crops. The farmer's manager thinks fertilizer products from distributor A contain more of the nitrogen that his plants need than distributor B's fertilizer does. He takes two independent samples of five batches of fertilizer from each distributor and measures the amount of nitrogen in each batch. Fertilizer from distributor A contained 25 pounds per batch and fertilizer from distributor B contained 17 pounds per batch. Suppose the population standard deviation for distributor A and distributor B is five pounds per batch and six pounds per batch, respectively. Assume the distribution of nitrogen in fertilizer is normally distributed. Let µ1 and u2 represent the average amount of nitrogen per batch for fertilizer's A and B, respectively. Which of the following is an appropriate p-value? Multiple Choice 0.0365 0.0414 0.0110 0.0702arrow_forwardthe soil biogeochemistry in Californian salt marshes wished to explore how two of the most common plant species, pickleweed and pacific cordgrass, affected the accumulation of nitrogen in the soil. They measured the concentration of ammonium, a molecular form of organic nitrogen, in the soil, and measured or manipulated the density of pickleweed and cordgrass. Manipulations of ½ meter square plots (20 plots per manipulation) included removing all cordgrass (cordgrass removal), removing all pickleweed (pickleweed removal), or mixed (the control - nothing removed, thus mixed plots included a mixture of natural pickleweed and cordgrass). Boxplots of ammonium concentrations in each of the three manipulation treatments. Letters indicate differences among means as determined by a Tukey posthoc test following ANOVA. (b) Overall relationship between cordgrass stem density and soil ammonium content (includes data from all plot treatments). The solid black line and the gray shading represent the…arrow_forward
- Rivers in North Carolina contain small concentrations of mercury that can accumulate in fish over their lifetimes. The concentration of mercury in fish tissue can be obtained by catching fish and sending samples to a lab for analysis. A study was conducted on fish from the Waccamaw and Lumber Rivers to investigate mercury levels in tissues of largemouth bass. At several stations along each river a group of fish were caught, weighed and measured; in addition a filet from each fish was sent to a lab so that the tissue concentration of mercury could be determined. In all, 171 fish were caught at 15 different research stations along the Waccamaw and Lumber Rivers. Data from fish caught at one of these stations is shown in the following table: length weight 1616 47.0 1862 48.7 2855 55.7 1199 45.2 1320 44.7 1225 43.8 870 38.5 1455 45.8 1220 44.0 1033 40.4 Compute the correlation between length and weight for these fish. (Assume the correlation conditions have been…arrow_forwardRivers in North Carolina contain small concentrations of mercury that can accumulate in fish over their lifetimes. The concentration of mercury in fish tissue can be obtained by catching fish and sending samples to a lab for analysis. A study was conducted on fish from the Waccamaw and Lumber Rivers to investigate mercury levels in tissues of largemouth bass. At several stations along each river a group of fish were caught, weighed and measured; in addition a filet from each fish was sent to a lab so that the tissue concentration of mercury could be determined. In all, 171 fish were caught at 15 different research stations along the Waccamaw and Lumber Rivers. Data from fish caught at one of these stations is shown in the following table: length weight 1616 47.0 1862 48.7 2855 55.7 1199 45.2 1320 44.7 1225 43.8 870 38.5 1455 45.8 1220 44.0 1033 40.4 Compute the correlation between length and weight for these fish. (Assume the correlation conditions have been…arrow_forwardThe Department of Natural Resources (DNR) received a complaint from recreational fishermen that a community was releasing sewage into the river where they fished. These types of releases lower the level of dissolved oxygen in the river and hence cause damage to the fish residing in the river. An inspector from the DNR designs a study to investigate the fishermen’s claim. Fifteen water samples are selected at locations on the river upstream from the community and fifteen samples are selected downstream from the community. The dissolved oxygen readings in parts per million (ppm) are given in the following table.Upstream 5.2 4.8 5.1 5.0 4.9 4.8 5.0 4.7 4.7 5.0 4.6 5.2 5.0 4.9 4.7, Downstream 3.2 3.4 3.7 3.9 3.6 3.8 3.9 3.6 4.1 3.3 4.5 3.7 3.9 3.8 3.7 a.In order for the discharge to have an impact on fish health, there needs to be at least a 0.5 ppm reduction in the dissolved oxygen. Do the data provide sufficient evidence that there is a large enough reduction in the mean dissolved oxygen…arrow_forward
- Algebra: Structure And Method, Book 1AlgebraISBN:9780395977224Author:Richard G. Brown, Mary P. Dolciani, Robert H. Sorgenfrey, William L. ColePublisher:McDougal Littell