Questions and Answers of The Analysis Of Biological Data

There is evidence that higher consumption of foods containing chemicals called flavanols—including cocoa, red wine, green tea, and some fruits— increases brain function in several ways. Messerli
Cocaine is thought to affect the brain by blocking the dopamine transporter, increasing the amount of dopamine in the nerve synapse. To investigate this idea, Volkow et al. (1997) administered
Both of the variables in Assignment Problem 19 are measurements that include some measurement error.a. How would this measurement error affect the correlation between the two variables?b. What
If you are having trouble solving homework problems, should you sleep on it and try again in the morning? Huber et al. (2004) asked 10 participants to perform a complex spatial learning task on the
The following data are from a laboratory experiment by Smallwood et al. (1998) in which liver preparations from five rats were used to measure the relationship between the administered concentration
In an increasingly urban world, are there psychological benefits to biodiversity? Fuller et al. (2007) measured the number of plant, bird, and butterfly species in 15 urban green spaces of varying
Does stress age you? As part of an investigation, Epel et al. (2004) measured telomere length in blood mononuclear cells of healthy premenopausal women, each of whom was the biological mother and
Left-handed people have an advantage in many sports, and it has been suggested that left-handedness might have been advantageous in hand-tohand fights in early societies. (Left-handed people can get
According to the immunocompetence handicap hypothesis, males of a species evolve high reproductive effort to the point that they divert resources away from immune function. To test this, Simmons and
When measuring a correlation between two variables, under what circumstances would it be best to make and average several repeat measurements of each subject for a given variable rather than measure
Answer the following questions using the data for the godwits in Practice Problem 5.a. Adding 30 to each of the observations for males converts arrival dates to “days since March 1” rather than
Birds of many species retain the same breeding partner year after year. In some of these species, male and female partners migrate separately and spend the winter in different places, often thousands
Visually estimate the value of the correlation coefficient in each of the four following scatter plots.(a)(b)(c)(d) Y ...
Calculation practice: Spearman rank correlation. As human populations became more urban from prehistory to the present, disease transmission between people likely increased. Over time, this might
Calculation practice. Estimate a correlation coefficient. In their study of hyena laughter, or “giggling” (see Chapter 12, Assignment Problem 24), Mathevon et al. (2010) asked whether sound
Calculation practice: Standard error and hypothesis testing for a correlation. Refer to Practice Problem 1. Test whether there is a correlation in the population between giggle fundamental frequency
Tukey–Kramer tests carried out on the results in Practice Problem 15 yielded the accompanying table of results. Groups refer to the number of genotypes in the corresponding treatment.a. Fill in
In a field experiment designed to investigate the role of genetic diversity in ecosystems, Reusch et al. (2005) planted eelgrass in plots in a shallow estuary in the Baltic Sea. Eighteen eelgrass
Tsetse flies are the vectors of human sleeping sickness and animal trypanosomiasis in Africa. The tsetse fly species Glossina palpalis feeds on the blood of a variety of animals, including humans,
Pea aphids, Acyrthosiphon pisum, can be red or green. Weirdly, red aphids make carotenoids (red pigments) with genes that jumped from a fungus into the aphid genome some time during recent
One way to assess whether a trait in males has a genetic basis is to determine how similar the measurements of that trait are among his offspring born to different, randomly chosen females. In a lab
The bright yellow head of the adult Egyptian vulture (see the photo at the beginning of the chapter) requires carotenoid pigments. These pigments cannot be synthesized by the vultures, so they must
Use the data from Practice Problem 7 to solve this problem.a. Test whether mean PLP1 gene expression differs among the schizophrenia, bipolar, and control groups.b. What are your assumptions in
In European earwigs, the males sometimes have long pincers protruding from the end of their abdomens, as shown in the accompanying photo.In graphs (a)-(c), we have plotted three frequency
Suppose that a variable has a normal distribution, that the mean is 35 mm, and that 20% of the population is larger than 50 mm.a. What is the mode of this distribution?b. What is the median of this
Imagine a hypothetical experiment with multiple treatments but relatively small sample sizes within treatments. The goal is to test whether the treatment means are equal. Calculations and graphical
The ability to learn is a very useful skill, so it is not clear why more organisms have not evolved better learning abilities. One possibility is that learning is energetically expensive, and the
Females of the bumblebee species Bombus terrestris can change from a non-reproductive worker to a reproductively mature individual under certain social conditions. Blacher et al. (2017) carried out
Infection by parasitic worms such as helminths can affect the immune response in ways that increase the susceptibility of hosts to infection by bacteria and viruses. Hence, treatment against
Computer optional: Refer to the previous problem. Download the African buffalo BTB data set from the book website. Focus on the variable survival of those individuals who became infected with BTB in
Computer optional: Refer to the previous question. Download the isopod data set from the book website and conduct the following analyses.a. Calculate the hazard ratio of successful burrows relative
Each spring, 9-month-old desert isopods (Hemilepistus reaumuri) emerge from their natal burrows and walk many hundreds of meters before settling into a new burrow. Settling is mainly done by females,
Huntington disease is an inherited neurodegenerative disease caused by a mutation in the huntingtin gene. When did this mutation arise? García-Planells et al. (2005) found that most Spanish cases of
Identify which of the following cases would violate the assumptions of the Kaplan–Meier method.a. Patients are more likely to leave the study before the end of monitoring if they are relatively
Which of the following are true about the Kaplan–Meier method? Answer true or false.a. It assumes that the individuals in the study are randomly chosen from the population they represent.b. It
Refer to Assignment Problem 10. The following table lists log-likelihoods for a range of values of p between 0.1 and 0.3, in increments of 0.01.a. Using only our calculations based on these
The Mediterranean shrub Thymelaea hirsute has five sexual types, the most curious of which is “gender labile.” Such individuals change their predominant sex from year to year. Ramadan et al.
Sacktor et al. (2000) measured the neuropsychological performance of 33 HIV-positive patients undergoing antiretroviral therapy. Hand-use performance improved in 23 of the 33 patients but
Dispersal and the movement distance of organisms are sometimes described using a probability distribution known as the geometric distribution (see Practice Problem 7). For example, the following
Ants are capable of chemically discriminating between nestmates and non-nestmates. Ozaki et al. (2005) discovered sensory cells in the antennae of ants that respond only to the cuticular hydrocarbons
Life spans of individuals in a population often approximate an exponential distribution, a continuous probability distribution having probability density f(Y)=λe−λY, where λ is the mortality
Is the perception of eye-gazing in humans acquired through experience, or is it innate? To test this, Farroni et al. (2002) presented 17 infants (3–5 days old) with paired photographs of faces. The
Examine the accompanying plots. Each is based on hypothetical data from an experiment with a categorical factor A and a continuous covariate X. In each case, indicate which of the main effects and
Langford et al. (2006) investigated whether lab mice experiencing discomfort “empathize” with familiar mice also in discomfort. They conducted an experiment in which individual mice were given an
Were Neanderthals smaller-brained than modern humans? Estimates of cranial capacity from fossils indicate that Neanderthals had large brains, but also that they had a large body size. The
For each of the following scenarios, draw an interaction plot (like that in Figure 18.3-2) showing the results of a hypothetical experiment having two factors, A and B, each having two groups, in
In a study of the effects of commercial fishing on fish populations, Hsieh et al. (2006) measured the year-to-year coefficient of variation (CV) of larval population sizes of exploited and
The tortoise beetle Deloyala guttata feeds and lays eggs on leaves of the two morning glory species Ipomea pandurata and I. purpurea. Rausher (1984) investigated whether there was genetic variation
Does light environment have an influence on the development of color vision? The accompanying data, from Fuller et al. (2010), are measurements of the relative abilities of bluefin killifish from two
Females of the yellow dung fly, Scathophaga stercoraria, mate with multiple males, and the sperm of different males “compete” to fertilize her eggs. The last male to mate usually gains a
Certain natural populations of the plant Arabidopsis halleri have two genetically encoded leaf types. Some individuals have trichomes on the leaves (“hairy”) and others lack trichomes
In promiscuous species of mammals, such as deer mouse, the breeding success of males can be predicted from their testes size and the number of sperm they produce. Fisher et al. (2018) investigated
Heusner (1991) assembled the following data on the mass and basal metabolic rate of 17 species of primates, including the potto shown in the accompanying photo.Previous research has indicated that
You might think that increasing the nutrient resources available would elevate the number of plant species that an area could support, but the evidence suggests otherwise. The data in the
Previous evidence and some theory predict that the exponent β describing the relationship between metabolic rate and mass should equal 3/4. Using the data from Assignment Problem 20, test whether
The white forehead patch of the male collared flycatcher is important in mate attraction. Griffith and Sheldon (2001) found that the length of the patch varied from year to year. They measured the
Many species live in a patchwork of local populations separated by inhospitable habitat. Local populations naturally go extinct (but can be later recolonized). Probability of extinction can be
How do we estimate a regression relationship when each subject is measured multiple times over a series of X-values ? The easiest approach is to use a summary slope for each individual and then
Many species of beetle produce large horns that are used as weapons or shields. The resources required to build these horns, though, might be diverted from other useful structures. To test this,
The parasitic bacterium Pasteuria ramosa castrates and later kills its host, the crustacean Daphnia magna. The length of time between infection and host death affects the number of spores eventually
Theory in ecology predicts that species with a large number of individuals will be larger targets for diseases. Parker et al. (2015) tested the idea in grassland plants. They measured the abundance
Golenda et al. (1999) carried out a human clinical trial to investigate the effectiveness of a formulation of DEET (N,N-diethyl-m-toluamide) in preventing mosquito bites. The study applied DEET to
A lot of attention has been paid recently to portion size in restaurants, and how it may affect obesity in North Americans. Portions have grown greatly over the last few decades. But is this
Calculating the year of birth of cadavers is a tricky enterprise. One method proposed is based on the radioactivity of the enamel of the body’s teeth. The proportion of the radioisotope 14C in the
The warm temperatures of spring and summer arrive earlier now at high latitudes than they did in the past, as a result of human-caused climate change. One consequence is that many organisms start
Scarlet king snakes (left photo) are relatively harmless snakes from the southeastern United States. Most individuals have a conspicuous color pattern very similar to the extremely venomous coral
Dads transmit many more new mutations than do mothers to their babies at conception. These mutations occur from copying errors during sperm production. There is increasing interest in the effect of
Species that depend on specific thermal environments might be expected to shift their geographic ranges northward and uphill as the world gets warmer, to track the temperatures that are best for
The human immunodeficiency virus (HIV) has a very high mutation rate. What are the effects of individual mutations on the fitness of the virus? Theys et al. (2018) measured the effect of each of many
Dormant eggs of the zooplankton Daphnia survive in lake sediments for decades, making it possible to measure their physiological traits in past years. Hairston et al. (1999) extracted Daphnia eggs
When using analysis of variance, what are the main advantages of the following factors?a. Large sample size.b. Balanced design.
Head width was measured twice, in centimeters, on the random sample of 25 walking-stick insects described in Example 15.6. The data are as follows:a. Use ANOVA calculations to estimate the variance
An observational study gathered data on the rate of progression of multiple sclerosis in patients diagnosed with the disease at different ages. Differences in the mean rate of progression were tested
The table on the next page presents mean cone size (mass) of lodgepole pine in 16 study sites in three types of environments in western North America (Edelaar and Benkman 2006). The three
Huey and Dunham (1987) measured the running speed of fence lizards, Sceloporus merriami, in Big Bend National Park in Texas. Individual lizards were captured and placed in a 2.3-meter raceway, where
Mosquitoes contribute to more human deaths than any other organism, because they transmit diseases such as malaria, dengue fever, and yellow fever. Some of these diseases develop or grow inside the
Does adding math to a scientific paper make readers think that it has more value? Eriksson (2012) sent two abstracts of scientific papers to 200 people with postgraduate degrees. For each
The parasitoid wasp, Leptopilina heterotoma, injects eggs into young larvae of fruit flies, Drosophila melanogaster. One reaction by the flies is to self-medicate by consuming alcohol (ethanol),
Refer to Assignment Problem 25.a. Illustrate the (transformed) data in a graph. Add means and error bars showing standard errors of means.b. The table at the bottom of the page shows partial
Fiddler crabs are so called because males have a greatly enlarged “major” claw, which is used to attract females and to defend a burrow. Darnell and Munguia (2011) recently suggested that this
Refer to Assignment Problem 27 on fiddler crab claws.a. The table at the bottom of the page shows partial results of Tukey–Kramer multiple comparisons of means. In what way does this method differ
In some animal species, exposure to males reduces lifespan of females, because of the damage caused by harassment and male seminal fluids. In other species, exposure to other females is more harmful
Alston’s singing mouse (Scotinomys teguina) and Chiriquí singing mice (S. xerampelinus) inhabitnonoverlapping elevation zones in the mountains of Central America. Experiments by Pasch et al.(2013)
In the accompanying graph of a normal distribution, each of the two red areas represents one-sixth of the area under the curve. Estimate the following quantities from this graph:a. The mean.b. The
The table at the top of the page lists the means and standard deviations of several different normal distributions. For each distribution, calculate the probability of drawing a single Y value
The proportion of traffic fatalities resulting from drivers with high blood alcohol levels in 1982 was approximately normally distributed among U.S. states, with mean 0.569 and standard deviation
The crab spider. Thomisus spectabilis, sits on flowers and preys upon visiting honeybees, as shown in the photo at the beginning of the chapter. (Remember this the next time you sniff a wild flower.)
The following table lists the mean and standard deviation of several different normal distributions. In each case, a sample of 20 individuals was taken, as well as a sample of 50 individuals. For
Calculation practice: Confidence interval for a mean and one-sample t-testAs the world warms, the geographic ranges of species might shift toward cooler areas. Chen et al. (2011), studied recent
The time it takes an individual popcorn kernel to pop conforms to a normal distribution very closely. Assume that the mean time to popping is 165.0 seconds with a standard deviation of 92.1
Calculation practice: Confidence interval for variance. Refer to Practice Problem 1. Using the data, calculate the 95% confidence interval for the variance with the following steps.a. What does the
For each of the following, the mean, standard deviation, sample size, and desired confidence interval are given. Find the critical values of tt required for a confidence interval of the
Refer to Practice Problem 3. For each of the parts (a)–(e), find the two χ2 critical values necessary to calculate a confidence interval of the variance.Data from practice problem 3 For each of
Here are the data on wolf upper jaws from Practice Problem 5, in centimeters. There are 35 individuals in this data set. Assume that this variable is normally distributed.a. Draw a graph to confirm
Measurements of the distance between the canine tooth and last molar for 35 wolf upper jaws were made by a researcher. He found the 95% confidence interval for the mean to be 10.17 cm
The world’s largest terrestrial invertebrate is the coconut crab, Birgus latro, which lives on islands in the Indian and Pacific Oceans. (These crabs normally eat fruits, but they have been
In the data set on wolf upper jaws (Practice Problem 6), each measurement was actually the average of two measurements made on the left and right sides of the jaw of an individual wolf. Thus, a total
Community ecologists draw “food webs” to describe the predator and prey relationships between all organisms living in an area. A theoretical model predicts that a measure of the structure of food
As part of a larger study into the role of the hippocampus in memory, Fortin et al. (2004) devised a test that required rats to choose between two odors, one of which had previously been presented to
The following tables give the confidence intervals of either the standard deviation or variance from different samples. Provide the confidence interval of the other measure of spread (i.e., either

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