Effects of Light Exposure (Example 9) A study carried out by Baturin and colleagues looked at the effects of light on female mice. Fifty mice were randomly assigned to a regimen of 12 hours of light and 12 hours of dark (LD), while another fifty mice were assigned to 24 hours of light (LL). Researchers observed the mice for two year, beginning when the mice were two months old. Four of the LD mice and 14 of the LL mice developed tumors. The accompanying table summarizes the data.
a. Determine the percentage of mice that developed tumors from each group (LL and LD). Compare them and comment.
b. Was this a controlled experiment or an observational study? How do you know?
c. Can we conclude that light for 24 hours a day causes an increase in tumors in mice? Why or why not?
Want to see the full answer?
Check out a sample textbook solutionChapter 1 Solutions
Introductory Statistics (2nd Edition)
- Captivity can influence immunological responses in some mammals. Seeber et al. (2020) investigated various aspects of immunological responses in captive and free-ranging zebras. One aspect of the study involved samples of 12 free-ranging zebras from Namibia, 9 from Tanzania, and 38 captive zebras from various zoos in Europe. (All of these were non-lactating females.) One of the measured variables from blood samples was lysozyme concentration (μg/L). (Lysozyme is a biomarker of the immune response.) The researchers were interested in investigating possible differences in lysozyme concentration between zebras in the various locations. As part of the analysis, they carried out a one-way ANOVA on the lysozyme concentrations for the zebras from the 3 locations, and found the following output. Df Sum Sq Mean Sq F value Pr(>F) Location 2 50.65 25.33 42.24 6.54e-12Residuals 56 33.57 0.60 Suppose the assumptions of one-way ANOVA…arrow_forwardA clinical trial of gamma globulin in the treatment of children with Kawasaki syndrome randomized approximately half of the patients to receive gamma globulin. The standard treatment is an aspirin regimen; however, about one quarter of these patients developed coronary abnormalities even, under the standard treatment. The outcome of interest was the development of coronary abnormalities (CA) over a 7-week follow-up period. The following 2 x 2 table summarizes the results. a) Calculate the odds of developing coronary abnormalities for those who took gamma globulin. Calculate the odds of developing coronary abnormalities for those who took aspirin. (b) Calculate the sample OR for developing coronary abnormalities comparing those on gamma globulin compared to those on aspirin. (c) Investigators constructed the following logistic model: where Logit(i) = log [i / (1 - i) ] = = – 1.0076 – 1.4030 GG Does it make sense to interpret the intercept in this model? If…arrow_forwardA medical student at a community college in city Q wants to study the factors affecting the systolic blood pressure of a person (Y). Generally, the systolic blood pressure depends on the BMI of a person (B) and the age of the person A. She wants to test whether or not the BMI has a significant effect on the systolic blood pressure, keeping the age of the person constant. For her study, she collects a random sample of 150 patients from the city and estimates the following regression function: Y= 15.50 +0.90B + 1.10A. (0.48) (0.35) The test statistic of the study the student wants to conduct (Ho: B, =0 vs. H4: B, #0), keeping other variables constant is. (Round your answer to two decimal places.) At the 5% significance level, the student will v the null hypothesis. Keeping BMI constant, she now wants test whether the age of a person (A) has no significant effect or a positive effect on the person's systolic blood pressure. So, the test statistic associated with the one-sided test the…arrow_forward
- A deficiency of the trace element selenium in the diet can negatively impact growth, immunity, muscle and neuromuscular function, and fertility. The introduction of selenium supplements to dairy cows is justified when pastures have low selenium levels. Authors of a research paper supplied the following data on milk selenium concentration (mg/L) for a sample of cows given a selenium supplement (the treatment group) and a control sample given no supplement, both initially and after a 9-day period. Initial Measurement Treatment Control 11.4 9.1 9.6 8.7 10.1 9.7 8.5 10.8 10.2 10.9 10.6 10.6 11.9 10.1 9.9 12.3 10.7 8.8 10.2 10.4 10.3 10.9 11.4 10.4 9.3 11.6 10.6 10.9 10.9 8.3 After 9 Days Treatment Control 138.3 9.2 104 8.9 96.4 8.9 89 10.1 88 9.6 103.8 8.6 147.3 10.4 97.1 12.4 172.6 9.2 146.3 9.5 99 8.4 122.3 8.8 103 12.5 117.8 9.1 121.5 93 (a) Use the given data for the treatment group to determine if…arrow_forwardA deficiency of the trace element selenium in the diet can negatively impact growth, immunity, muscle and neuromuscular function, and fertility. The introduction of selenium supplements to dairy cows is justified when pastures have low selenium levels. Authors of a research paper supplied the following data on milk selenium concentration (mg/L) for a sample of cows given a selenium supplement (the treatment group) and a control sample given no supplement, both initially and after a 9-day period. Initial Measurement Treatment Control 11.3 9.1 9.7 8.7 10.1 9.7 8.5 10.8 10.4 10.9 10.7 10.6 11.8 10.1 9.8 12.3 10.6 8.8 10.4 10.4 10.2 10.9 11.3 10.4 9.2 11.6 10.7 10.9 10.8 8.2 After 9 Days Treatment Control 138.3 9.4 104 8.8 96.4 8.8 89 10.1 88 9.7 103.8 8.7 147.3 10.3 97.1 12.3 172.6 9.4 146.3 9.5 99 8.3 122.3 8.9 103 12.5 117.8 9.1 121.5 93 (a) Use the given data for the treatment group to determine if…arrow_forwardA deficiency of the trace element selenium in the diet can negatively impact growth, immunity, muscle and neuromuscular function, and fertility. The introduction of selenium supplements to dairy cows is justified when pastures have low selenium levels. Authors of a research paper supplied the following data on milk selenium concentration (mg/L) for a sample of cows given a selenium supplement (the treatment group) and a control sample given no supplement, both initially and after a 9-day period. Initial Measurement Treatment Control 11.2 9.1 9.6 8.7 10.1 9.7 8.5 10.8 10.3 10.9 10.6 10.6 11.7 10.1 9.7 12.3 10.8 8.8 10.3 10.4 10.4 10.9 11.2 10.4 9.4 11.6 10.6 10.9 10.7 8.4 After 9 Days Treatment Control 138.3 9.3 104 8.7 96.4 8.7 89 10.1 88 9.6 103.8 8.6 147.3 10.2 97.1 12.2 172.6 9.3 146.3 9.5 99 8.2 122.3 8.9 103 12.5 117.8 9.1 121.5 93 (a) Use the given data for the treatment group to determine if there…arrow_forward
- You are concerned that nausea may be a side effect of Tamiflu, but you cannot just give Tamiflu to patients with the flu and say that nausea is a side effect if people become nauseous. This is because nausea is common for people who have the flu. From past studies you know that about 32% of people who get the flu experience nausea. You collected data on 2494 patients who were taking Tamiflu to relieve symtoms of the flu, and found that 870 experienced nausea. Use a 0.01 significance level to test the claim that the percentage of people who take Tamiflu for the relief of flu symtoms and experience nausea is greater than 32%. a) Identify the null and alternative hypotheses? Ho: ? v Ha: ? v b) What type of hypothesis test should you conduct (left-, right-, or two-tailed)? O left-tailed O right-tailed O two-tailed c) Identify the appropriate significance level. Submit Question 3.arrow_forwardOne variety of corn is genetically modified to produce chemicals for defense against predators. The standard corn contains the same standard genotype, but without genetic modification for the chemicals. The two types of corn are then planted in randomly placed adjacent plots across a single field. The amount of predators that are present when the corn has matured are then recorded. The data that was recorded of the predators present among each type are listed. Has genetic alterations decreased the amount of predators for the altered genotype? Normality tests for the populations of both contain a p value less than 0.05. The given alpha is 0.05 Modified Corn (20, 18, 26, 23, 17, 23, 22) Standard Corn (89, 64, 102, 96, 56, 77, 84, 59) use an F test to determine if the variance between the 2 lists are different. Based on this result, state the correct 2 sample parametric test to be used. State the null and alternative. Show calculations while rounding to two decimal points.What is the…arrow_forwardSuppose a study investigated the effects of vitamin A, vitamin C, and omega-3 fatty acids supplements on improving eye health and vision. 300 adults volunteered to take part in the study. In the study, participants were randomly assigned to one of 3 different levels of Vitamin A (Level A, Level B, or Level C) and randomly assigned to one of 2 different levels of Vitamin C (Level 1 or Level 2) and randomly assigned to one of 2 different levels of omega-3 fatty acid (Level I or Level II). a. Identify the subjects of the study. b. Identify the factor(s) for the study and the number of treatment level(s) for each factor. c. How many different treatment groups are there in this study?arrow_forward
- People who eat lots of fruits and vegetables have lower rates of colon cancer than those who eat little of these foods. Fruits and vegetables are rich in "antioxidants" such as vitamins A, C, and E. Will taking antioxidants help prevent colon cancer? A clinical trial studied this question with 864 people who were at risk for colon cancer. The subjects were divided into four groups: daily beta-carotene, daily vitamins C and E, all three vitamins every day, and daily placebo. After four years, the researchers were surprised to find no significant difference in colon cancer among the groups. What are the explanatory and response variables in this experiment? Explanatory variable Response variable Answer Bank development of colon cancer vitamin regimen the sample size quantity of fruits and vegetables consumedarrow_forwardA health officer is trying to study the malaria situation of Zambia. From the records of seasonal blood survey (SBS) results he came to understand that the proportion of people having malaria in Zambia was 3.8% in 2015. The size of the sample considered was 15,000. He also realized that during the year that followed (2016), blood samples were taken from 10,000 randomly selected persons. The result of the 2016 seasonal blood survey showed that 200 persons were positive for malaria. Help the Health officer in testing the hypothesis that the malaria situation of 2016 did not show any significant difference from that of 2015 (take the 5% level of significance).arrow_forwardA random sample of 1000 people with known allergies to poison ivy participated in a recent study. Oil from the poison ivy plant was rubbed on a patch of skin. For 500 of the subjects, the oil it was washed off within 5 minutes. For the other 500 subjects, the oil was washed off after 5 minutes. Observed reactions were recorded as "none," "mild," or "strong." The results are summarized in the following table. Reaction Within 5 Minutes After 5 Minutes Row Total NoneMildStrong 4055144 6833894 473389138 Column Total 500 500 1000 Suppose a person selected at random from this sample of 1000 subjects. What is the probability that a strong reaction was observed, given that the oil was washed off within 5 minutes? (Select below). 0.188 0.044 0.088 0.319arrow_forward
- Linear Algebra: A Modern IntroductionAlgebraISBN:9781285463247Author:David PoolePublisher:Cengage LearningHolt Mcdougal Larson Pre-algebra: Student Edition...AlgebraISBN:9780547587776Author:HOLT MCDOUGALPublisher:HOLT MCDOUGALGlencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw Hill
- Big Ideas Math A Bridge To Success Algebra 1: Stu...AlgebraISBN:9781680331141Author:HOUGHTON MIFFLIN HARCOURTPublisher:Houghton Mifflin Harcourt