wileyplus stats150

student survey variables in the dataset StudentSurvey, seven of the variables are identified as categorical or quantitative. the remaining variables are: 1. year (first year, sophomore, junior, senior) 2. height (in inches) 3. weight (in pounds) 4. siblings (# of siblings a person has) 5. verbalSAT (score on the verbal section of the sat exam) 6. mathSAT (score on the math section of the sat exam) 7. SAT (sum of the scores on the verbal and math sections of the sat exam) 8. higherSAT (which is higher, math sat or verbal sat score?)

1. year: categorical 2. height: quantitative 3. weight: quantitative 4. siblings: quantitative 5. verbalSAT: quantitative 6. mathSAT: quantitative 7. SAT: quantitative 8. higherSAT: categorical

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do you use a food delivery app? a 2019 study conducted by emarketer asked 800 us smartphone user whether they had used a food delivery app at least once in the last month. the survey also asked which food delivery app, if any, was used. the survey showed that 16.3% of respondents had used a food delivery app in the last month. of those that had used on, 27.6% used doordash, 26.7% used grubhub, 25.2% used ubereats, while the rest used another. a) what is the sample? b) what is the intended population? c) how many cases are there? d) how many variables are mentioned? e) how many of the variables are categorical? f) how many of the variables are quantitative?

a) the 800 people who answered the survey b) all us smartphone users c) 800 d) 2 e) 2 f) 0

in a random samples of 3500 canadian consumers, about 71% report that they regularly stream music. a) is the sample likely to be representative of all canadian consumers? b) is it reasonable to generalize this result and estimate that about 71% of all canadian consumers regularly stream music?

a) yes b) yes

does chocolate milk come from brown cows? the us national dairy council, a dairy advocacy group, conducted a survey that appears to show that 7% of americans (which is about 16.4 mil people) believe that chocolate milk comes from brown cows. this result was picked up by a shared widely, including by CNN.com, the washington post, the today show, and npr (national public radio). the goal of the survey was to find some fun facts to share and the advocacy group has not made the full survey results, or the sampling method, publicly available. a) do you think it is likely that there is sampling bias in this study? without knowing how the sample was determined, can we know if it is appropriate to generalize to all americans? b) while we don't know how the sample was determined, interviewers on npr were able to find out how the question was phrased. survey respondents were asked to select one option to the following: "where does chocolate milk come from? (a) brown cows, (b) black and white spotted cows, (c) I don't know." do you think the way the question was worded might have biased results?

a) yes, it is likely that there is sampling bias and it is not appropriate to generalize. b) yes, there is wording bias.

the proportion for a population is

p

the proportion for a sample is

p^

state whether the data are best described as a population or a sample. a subscription-based music website tracks its total number of active users.

population

the population is incoming students at a particular university. the name of each incoming student is thrown into a hat, the names are mixed, and 25 names (each corresponding to a different student) are drawn from the hat. state whether or not the sampling method described produced a random sample from the given population.

random

we introduce a study by researchers from harris interactive who were interested in determining what percent of people wash their hands after using the washroom. they collected data by standing in public restrooms and pretending to comb their hair or put on make-up as they observed patrons behavior. public restrooms were observed at turners field in atlanta, penn station and grand central station in new york, the museum of science and industry and the shedd aquarium in chicago, and the ferry terminal farmers market in san francisco. of the over 6000 people whose behavior was observed, 85% washed their hands. women were more likely to wash their hands: 93% of women washed, while only 77% of men did. the museum of science and industry in chicago had the highest hand-washing rate, while men at turners field in atlanta had the lowest. a) identify each of the following variables as categorical or quantitative: i. the variable indicating whether or not the person washed their hands. ii. the variable indicating the gender of the individual. iii. the variable indicating the location of the observation. b) in a separate telephone survey of more than 1000 adults, more than 96% said they always wash their hands after using a public restroom. why do you think there is such a discrepancy in the percent from the telephone survey compared to the percent observed?

a) i. categorical ii. categorical iii. categorical b) self-reported behavior is often inaccurate and biased.

what proportion of college students have a paying job? the higher education research institute conducts your first college year survey every year. the 2018 survey included 5204 first-year, full- time college students. their responses to a question about whether they worked at a paying job while attending college are given in the table below. a) what proportion do not work at a paying job? b) what proportion do work at a paying job (either on campus or off campus)? c) make a relative frequency table of this variable: work on campus work off campus does not work total

a) 0.509 b) 0.491 c) relative frequency: works on campus: 0.276 works off campus: 0.215 does not work: 0.509 total: 1.00

in june 2018, a poll asked a random sample of 1000 us adults whether global warming will be a serious problem for the united states. the results show that 51% think global warming will be a very serious problem, 27% think it will be a somewhat serious problem, and 21% think it will not be a serious problem. a) what is the sample? b) what is the intended population? c) is it reasonable to generalize this result and estimate that 21% of us adults think that global warming will not be a serious problem for the united states?

a) 1000 us adults that were contacted. b) all us adults. c) yes

in this exercise, a two-way table is shown for two groups. 1 and 2, and two possible outcomes, a and b. outcome a outcome b total group 1 30 20 50 group 2 40 110 150 total 70 130 200 **round your answers to 3 decimal places** a) what proportion of all cases had outcome a? b) what proportion of cases are in group 1? c) what proportion of cases in group 1 had outcome b? d) what proportion of cases who had outcome a were in group 2?

a) 70/200= 0.35 b) 50/200= 0.25 c) 20/50= 0.4 d) 40/70= 0.571

employment statistics in the us are often based on two nationwide monthly surveys: the current population survey (cps) and the current employment statistics (ces) survey. the cps samples approximately 60,000 us households and collets the employment status, job type, and demographic information of each resident in the household. the ces survey samples 140,00 non-farm businesses and government agencies and collects the number of payroll jobs, pay rates, and relation information from each firm. a) what is the population in the cps survey? b) what is the popualtion in the ces survey? c) i. do larger companies tend to have higher salaries? ii. what percentage of americans are self-employed? iii. are married men more or less likely to be employed than single men?

a) all us households b) all non-farm business and government agencies c) i. ces ii. cps iii. cps

what proportion of canadian adults graduate high school? canada conducts a census every five years. the 2016 canadian census shows that 81.7% of canadian adults have a secondary or equivalent degree. a) give the correct notation for this value b) write the value as a proportion without a percent sign

a) p since this is a proportion for a population b) 0.187

can experiences of parents affect future children? new studies1 suggest that they can: early life experiences of parents appear to cause permanent changes in sperm and eggs. In one study, some male rats were fed a high-fat diet with 43% of calories from fat (a typical American diet), while others were fed a normal healthy rat diet. Not surprisingly, the rats fed the high-fat diet were far more likely than the normal-diet rats to develop metabolic syndrome (characterized by such things as excess weight, excess fat, insulin resistance, and glucose intolerance.) What surprised the scientists was that the daughters of these rats were also far more likely to develop metabolic syndrome than the daughters of rats fed healthy diets. None of the daughters and none of the mothers ate a high-fat diet and the fathers did not have any contact with the daughters. The high-fat diet of the fathers appeared to cause negative effects for their daughters. One variable is whether or not the male was fed a high-fat diet or a normal diet and another variable is whether or not the daughters developed metabolic syndrome. a) Is the type of diet variable categorical or quantitative? b) Is metabolic status of the daughters variable categorical or quantitative? c) Is metabolic status of the daughters the explanatory variable or the response variable?

a. categorical b. categorical c. response variable

spiders regularly engage in spider foreplay that does not culminate in mating. Male spiders mature faster than female spiders and often practice the mating routine on not-yet-mature females. Since male spiders run the risk of getting eaten by female spiders, biologists wondered why spiders engage in this behavior. In one study,1 some spiders were allowed to participate in these near-matings, while other maturing spiders were isolated. When the spiders were fully mature, the scientists observed real matings. They discovered that if either partner had participated at least once in mock sex, the pair reached the point of real mating significantly faster than inexperienced spiders did. (Mating faster is, apparently, a real advantage in the spider world.) One variable is whether or not the spider engaged in mock-sex. Another is the length of time for real mating once the spider is fully mature. a) Is the variable whether or not the spider engaged in mock sex categorical or quantitative? b) Is the variable length of time for real mating categorical or quantitative? c) Is the variable length of time for real mating the explanatory variable or the response variable?

a. categorical b. quantitative c. response variable

state whether the following claim is one of association and causation, association only, or neither association nor causation. cell phone radiation leads to deaths in honey bees.

association with causation

state whether the following claim is one of association and causation, association only, or neither association nor causation. daily exercise improved mental performance.

association with causation

indicate whether we should trust the results of the following study. is the method of data collection biased? send an email to a random sample of students at a university asking them to reply to the question: "do you think this university should fund an ultimate frisbee team?" a small number of students reply. use the replies to estimate the proportion of all students at the university who support this use of funds.

biased

indicate whether we should trust the results of the following study. is the method of data collection biased? take 13 apples off the top of a truckload of apples and measure the amount of bruising on those apples to estimate how much bruising there is, on average, in the whole truckload.

biased

is the following variable categorical or quantitative? people in the city are asked if they support a new recycling law.

categorical

is the following an experiment or an observational study? to examine whether playing music in a store increases the amount customers spend, we randomly assign some stores to play music and some to stay silent and compare the average amount spent by customers.

experiment

a relationship between two variables is described below. we can think of one variable as helping to explain the other. is the indicated variable the explanatory variable or the response variable? lung capacity and number of years smoking cigarettes. number of years smoking cigarettes is the:

explanatory variable

state whether the following claim is one of association and causation, association only, or neither association nor causation. among college students, no link found between number of friends on social networking websites and size of the university.

neither association nor causation

indicate whether we should trust the results of the following study. is the method of data collection biased? take a random sample of one type of printer and test each printer to see how many pages of text each printer will print before the ink runs out. use the average from the sample to estimate how many pages, on average, all printers of this type will last before the ink runs out.

not biased

the population is all people who visit the website CNN.com. all visitors to the website are invited to take part in the daily online poll. state whether or not the sampling method described produced a random sample from the given population.

not random

the population is all trees in a forest. we walk through the forest and pick out trees that appear to be representative of all the trees in the forest. state whether or not the sampling method described produced a random sample from the given population.

not random

gene actn3 question

observational study

is the following an experiment or an observational study? to examine whether eating brown rice affects metabolism, we ask a random sample of people whether they eat brown rice and we also measure their metabolism rate.

observational study

the exercise provides information about data in a survey of students. the survey included 70 students who smoke and 329 who don't. find p^, the proportion who smoke. round your answer to three decimal places.

p^ = 0.175 proportion in a category = # in that category / total # 70+ 329= 399 70/399= 0.175

is the following variable categorical or quantitative? measure the shelf life of bunches of bananas (the number of days until the bananas go bad) for a large sample.

quantitative

the population is approximately 23,000 protein-coding genes in human DNA. each gene is assigned a number (from 1 to 23,000), and computer software is used to randomly select 100 of these numbers yielding a sample of 100 genes. state whether or not the sampling method described produced a random sample from the given population.

random

a relationship between two variables is described below. we can think of one variable as helping to explain the other. is the indicated variable the explanatory variable or the response variable? amount of fertilizer used and the yield of a crop. yield of the crop is the:

response variable

in this exercise, data from the StudentSurvey dataset is given. of the 361 students who answered the question about the number of piercings they had in their body, 188 had no piercings, 82 had one or two piercings, and the rest had more than two. construct a relative frequency table of the data using the categories given. give the relative frequencies rounded to three decimal places.

response: relative frequency: no piercing 0.521 1 or 2 piercings 0.227 more than 2 piercings 0.252 total 1.00

state whether the data are best described as a population or a sample. to estimate size of trout in a lake, an angler records the weight of 9 trout he catches over a weekend.

sample