Questions and Answers of The Analysis Of Biological Data

Identify the consequences (i.e., increase, decrease, or none) that the following procedures are likely to have on both bias and sampling error in an observational study.a. Matching sampling units
In a study of the effects of marijuana on the risk of cancer in oral squamous cells, Rosenblatt et al. (2004) examined 407 recent cases of the cancer from western Washington state. They also randomly
After stinging its victim, the honeybee leaves behind the barbed stinger, poison sac, and muscles that continue to pump venom into the wound.Visscher et al. (1996) compared the effects of two methods
What is the justification for including extreme doses well outside the range of exposures encountered by people at risk in a dose–response study on animals of the effects of a hazardous substance?
A strain of sweet corn has been genetically modified with a gene from the bacterium Bacillus thuringiensis (Bt) to express the protein Cry1Ab, which is toxic to caterpillars that eat the leaves.
In the Bt and monarch study described in Practice Problem 11, how many plots would you plan per treatment if your goal were to carry out a test having 80% power to reject the null hypothesis of no
The experiment described in Example 12.2 compared antibody production in 13 male red-winged blackbirds before and after testosterone implants. The units of antibody levels were log 10−3 optical
Consider the results of a six-year observational study that documented health changes related to homeopathic care (Spence and Thompson 2005).Homeopathic treatment was defined as “stimulating the
The fish species Astyanax mexicanus includes blind, cave-inhabiting populations whose eyes degenerate during embryonic development. To understand how eye degeneration worked, Yamamoto and Jeffery
Blaustein et al. (1997) used a field experiment to investigate whether increased UV-B radiation was a cause of amphibian deformities (see the photo at the beginning of this chapter). They measured
In 1976, Ewan Cameron and Linus Pauling (the only person to have won two unshared Nobel Prizes) published a paper showing that vitamin C was an effective treatment for some kinds of cancer. They
In the 1960s and before, many lakes were becoming “eutrophic,” meaning that they were producing so much algae and cyanobacteria that they were turning into green, soupy waters in which other
Identify the consequences (i.e., increase, decrease, or none) that the following procedures are likely to have on both bias and sampling error in an experimental study.a. Assigning treatment to
Two clinical trials were designed to test the effectiveness of laser treatment for acne. Seaton et al. (2003) randomly divided participants into two groups. One group received the laser treatment,
Identify the consequences (i.e., increase, decrease, or none) that the following procedures are likely to have on both bias and sampling error in an observational study.a. Planning for data
Identify which goal of experimental design (i.e., reducing bias or limiting effects of sampling error) is aided by the following procedures:a. Including extreme treatment levels.b. Using a paired
Identify the particular feature that defines each of the following experimental designs, and list the specific advantages provided by the feature you identify.a. Factorial design.b. Randomized
Kirsch (2010) argues that in double-blind clinical trials to test the effects of antidepressants, a large fraction of patients figure out whether they have been given the antidepressant or the
Michalsen et al. (2003) conducted a study to examine the effects of “leech therapy” for pain resulting from osteoarthritis of the knee. Two treatments were randomly assigned to 51 patients with
Design a study to compare the reaction times of the left and right hands of right-handed people using a computer mouse. Two design choices are available to you. In the first, a sample of right-handed
Identify the single most significant flaw in each of the following experimental designs. Use statistical language to identify what’s missing.a. In a test of the effectiveness of acupuncture in
Young et al. (2006) took measurements of subordinate female meerkats to determine the changes in reproductive physiology experienced by females that are evicted from their social groups. They
In 1899, the British Medical Journal (page 933) reported the results of a medical procedure involving the subcutaneous infusion of a salt solution for the treatment of extremely severe pneumonia:
Diet restriction is known to extend life and reduce the occurrence of age-related diseases. To understand the mechanism better, you propose to carry out a study to look at the separate effects of age
Calculation practice: Analysis of variance. Many humans like the effect of caffeine, but it occurs in plants as a deterrent to herbivory by animals. Caffeine is also found in flower nectar, and
Calculation practice: Analyze results from a Tukey–Kramer test. Using the same data as in Practice Problem 1, use the results from a Tukey–Kramer test to illustrate which of the pairs of groups
Calculation practice: Repeatability. The following anonymized data show the midterm and final exam grades (%) for eight undergraduate students from a biostatistics class at a major university. The
An important issue in conservation biology is how dispersal among populations influences the persistence of species in a fragmented landscape. Molofsky and Ferdy (2005) measured this in the annual
Calculation practice: Finding the probability of a range of values using the normal distribution. The natural log of growth (change in radius per year in mm) of Engelmann spruce is approximately
Spot the flaw. In a newer study of “high-rise syndrome” (see Chapter 1), Vnuk et al. (2004) reported injury rates of 119 fallen cats brought to a veterinary clinic in Zagreb, Croatia. The
For each of the graphs shown below, based on hypothetical data, identify the type of graph and say whether or not the two variables exhibit an association. Explain your answer in each
Estimate by eye the relative frequency of the shaded areas in each of the following histograms.(a)(b)(c) Relative frequency 0 2 3 4
Imagine that you have carried out a study to determine whether sons resemble their mothers. In each of 18 independent trials, you showed a participant a photo of one boy and photos of two adult
The gene Prdm9 is thought to regulate hotspots of recombination (crossing over) in mammals, including humans. In the people of Han Chinese descent living in the Los Angeles area there are five
Imagine that an effect was detected in every study listed in Problem 9 (a– e). In which of the studies would the researchers be justified in concluding that the effect was caused by the explanatory
Each of the examples (a–e) in Problem 9 involves estimating or testing an association between two variables. For each of the examples, list the two variables, and state whether each is categorical
Using a graphical method from this chapter, draw three frequency distributions: one that is symmetric, one that is skewed, and one that is bimodal.a. Identify the mode in each of your frequency
In the southern elephant seal, males defend harems that may contain hundreds of reproductively active females. Modig (1996) recorded the numbers of females in harems in a population on South Georgia
Draw scatter plots for invented data that illustrate the following patterns:a. Two numerical variables that are positively associated.b. Two numerical variables that are negatively
The following data are the occurrences in 2018 of the different species groups in the list of endangered and threatened species under the U.S. Endangered Species Act (U.S. Fish and Wildlife Service
A study by Miller et al. (2004) compared the survival of two kinds of Lake Superior rainbow trout fry (babies). Four thousand fry were from a government hatchery on the lake, whereas 4000 more fry
Human diseases differ in their virulence, which is defined as their ability to cause harm. Scientists are interested in determining what features of different diseases make some more dangerous to
Can environmental factors affect the incidence of schizophrenia? A recent project measured the incidence of the disease among children born in a region of eastern China: 192 of 13,748 babies born in
Examine the figure below, which indicates the date of first occurrence of rabies in raccoons in the townships of Connecticut, measured by the number of months following March 1, 1991.a. Identify the
Each of the following graphs illustrates an association between two variables. For each graph, identify (1) The type of graph, (2) The explanatory and response variables, and (3) The type of data
The following graph is from a study of the proficiency of two groups of people on a complex visual task involving “rhythmic temporal patterns similar to Morse code” (Saenz & Koch 2008). One
The following data are from the Cambridge Study in Delinquent Development (see Problem 22).They examine the relationship between the occurrence of convictions by the end of the study and the family
Each of the following graphs illustrates an association between two variables. For each graph, identify:(1) The type of graph,(2) The explanatory and response variables, and(3) The type of data
Spot the flaw. In an experimental study of gender and wages, Moss-Racusin et al. (2012) presented professors from research-intensive universities each with a job application for a laboratory manager
Moths are fatally attracted to human light sources, including fire and street lights. If it is a significant source of mortality, we might predict that moth populations living close to human
“Animal personality” has been defined as the presence of consistent differences between individuals in behaviors that persist over time. Do sea anemones have it? To investigate, Briffa and
The following data are from Mattison et al. (2012), who carried out an experiment with rhesus monkeys to test whether a reduction in food intake extends life span (as measured in years). The data are
Calculation practice: Box plots. Here is another sample of systolic blood pressure (in units of mm Hg), this time with 101 data points. The mean is 122.73 and the standard deviation is 13.83.a. What
Calculation practice: Basic descriptive stats. Systolic blood pressure was measured (in units of mm Hg) during preventative health examinations on people in Dallas, Texas. Here are the measurements
A review of the performance of hospital gynecologists in two regions of England measured the outcomes of patient admissions under each doctor’s care (Harley et al. 2005). One measurement taken was
The data displayed in the plot below are from a nearly complete record of body masses of the world’s native mammals (in grams, then converted to log-base 10; Smith et al. 2003). The data were
The following data are measurements of body mass, in grams, of finches captured in mist nets during a survey of various habitats in Kenya, East Africa (Schluter 1988).a. Calculate the mean body mass
Mehl et al. (2007) wired 396 men and women volunteers with electronically activated recorders that allowed the researchers to calculate the number of words each individual spoke, on average, per 17-
The spider data in Example 3.2 consist of pairs of measurements made on the same subjects. One measurement is running speed before amputation and the second is running speed after amputation.
Refer to the previous problem. If you were to convert all of the observations of change in running speed from cm/s into mm/s, how would this changea. The mean?b. The standard deviation?c. The
Niderkorn’s (1872; from Pounder 1995) measurements on 114 human corpses provided the first quantitative study on the development of rigor mortis. The data in the following table give the number of
The following graph shows the population growth rates of the 204 countries recognized by the United Nations. Growth rate is measured as the average annual percent change in the total human population
Refer to the previous problem.a. Draw a box plot using the information provided in the graph in that problem.b. Label three features of this box plot.Data from previous problemThe following graph
Spot the flaw. The accompanying table shows means and standard deviations for the length of migration on a microgel of 20 lymphocyte cells exposed to X-irradiation. The length of migration is an
Researchers have created every possible “knockout” line in yeast. Each line has exactly one gene deleted and all the other genes present (Steinmetz et al. 2002). The growth rate—how fast the
The snake undulation data of Example 3.1 were measured in Hz, which has units of 1/s (cycles per second). Often frequency measurements are expressed instead as angular velocity, which is measured in
If all the measurements in a sample of data are equal, what is the variance of the measurements in the sample?
Reddit user sp_ace popped some popcorn and recorded how long it took each kernel to pop. Here is a frequency table for the time to popping for this popcorn.a. What is the mean time to popping for
How long do you hug somebody? Nagy (2011) measured the duration of spontaneous embraces at the 2008 Summer Olympic Games in Beijing, China. The data are the durations of hugs, in seconds, of athletes
Calculation practice: Standard error of the mean and approximate confidence intervals for the mean. We will use the same data for systolic blood pressure collected for Calculation Practice Problem 1
Seven of the 100 human genes that we sampled randomly from the human genome (in Example 4.1) were found to occur on the X chromosome. The sample fraction of genes on the X was thus p^ = 7/100=0.07
Calculation practice: Bayes’ theorem. Refer to Practice Problem 4. Use the following steps to calculate the probability that a Canadian man smoked, given that he had been diagnosed with lung
Studies have shown that the probability that a man washes his hands after using the restroom at an airport is 0.74, and the probability that a woman washes hers is 0.83 (American Society for
An imaginary researcher examined the 18 largest mammal species in the Americas that occur both on the mainland and on islands. Sixteen of the mammal species were smaller on islands than on the
Some people are hypersensitive to the smell of asparagus, and can even detect a strong odor in the urine of a person who has recently eaten asparagus. This trait turns out to have a simple genetic
Why do we “fail to reject H0 rather than “accept H0 after a test in which the P-value is calculated to be greater than α ?
A clinical trial was carried out to test whether a new treatment affects the recovery rate of patients suffering from a debilitating disease. The null hypothesis “H0 The treatment has no effect”
As neuronal activity increases in the brain, blood flow to the brain also rises to meet the increasing demands for oxygen. Sheth et al. (2004) measured blood dynamics in the somatosensory cortex of
About 30% of people cannot detect any odor when they sniff the steroid androstenone, but they can become sensitive to its smell if exposed to the chemical repeatedly. Does this change in sensitivity
Assume that a null hypothesis is true. Which one of the following statements is true?a. A study with a larger sample is more likely than a smaller study to get the result that P < 0.05.b. A study
Assume that a null hypothesis is false. Which one of the following statements is true?a. A study with a larger sample is more likely than a smaller study to get the result that P < 0.05.b. A study
Calculation practice: Standard error of a proportion. Canner et al. (2014) surveyed U.S. emergency room data to better understand who is most likely to be injured by fireworks. Of the 25,675
Calculation practice: Confidence interval for a population proportion. In a study in Scotland (as reported by Devlin 2009), researchers left a total of 240 wallets around Edinburgh, as though the
Calculation practice:x2 goodness-of-fit test to a Poisson distribution. Your friend is writing a computer program to place individuals randomly on a spatial landscape, where every individual is
The white “Spirit” black bear (or Kermode), Ursus americanus kermodei, differs from the ordinary black bear by a single amino acid change in the melanocortin 1 receptor gene (MC1R). In this
Refer to Practice Problem 1.a. Produce a graph illustrating the probability distribution of the number of vancomycin-resistant isolates when seven isolates are randomly sampled from the U.S.
Luijckx et al. (2012) discovered that resistance to the bacterial parasite Pasteuria ramosa is genetically variable in the common freshwater crustacean Daphnia magna. To investigate the genetic basis
A scientist sets up an experiment with Drosophila that requires her to make a measurement on each fly every day until all the flies are dead.She knows that flies in her stock typically die at a rate
The study of the spatial distribution of vegetation often makes use of random samples of “quadrats,” rectangular plots of fixed size placed at random over the sampling region (e.g., a field or
A study of 6,839,854 births in the United States found a total of 6522 babies were born with a finger defect, either syndactyly (fused fingers), polydactyly (extra fingers), or adactyly (fewer than
Calculation practice: x2 contingency analysis. Married couples often split up after one member is diagnosed with a catastrophic disease, such as terminal cancer or a brain tumor. Does the frequency
The hypothetical plots below show the relative frequencies of subjects assigned to two experimental groups (treatment and control). The frequency of negative outcomes (red) and positive outcomes
Seeds fall on a landscape that contains 70% barren rock. The remainder of the landscape is suitable habitat for the seeds to germinate. Assume that the location where a seed falls in this landscape
When one generation reproduces to form the next, the frequencies of alleles in the population can change by chance from generation to generation in a process called random genetic drift. An
A researcher wished to estimate the fraction of students in a large high school who have used illegal drugs on at least one occasion. He carried out his survey through interviews with students. To
The following data are scores reflecting the number of young cod that recruited (grew to the catchable size) to the North Sea population in different years (Beaugrand et al. 2003). Scores are
Some people who are having a heart attack do not experience chest pain, although most do. A study of people admitted to emergency rooms with heart attacks compared the death rates of people who had
Birds of the Caribbean islands of the Lesser Antilles are descended from immigrants originating from larger islands and the nearby mainland. The data presented here are the approximate dates of
A research project investigated the ability of tobacco hornworm caterpillars to learn to associate a particular odor with a mild electric shock. After training five caterpillars, each was placed at
When the performances of individuals, or preferences for products, are judged in sequence by subjective criteria (think music audition or dance competition), does position in the sequence affect the

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