A nutritionist would like to estimate the mean number of servings of vegetables the typical person in her community consumes daily. She has an intern select a random sample of 39 clients who come to her ofce for nutritional coaching sessions. The nutritionist has the intern ask them how many servings of vegetables they consume daily. She nds they consume an average of 5 servings of vegetables daily. (a) This technique will introduce what type of bias? nonresponse bias " response bias ' selection bias no bias is being introduced (b) Fill in the blank. The value, 5, is ---Select-- a . (c) Fill in the blank. The variable, number of servings of vegetables consumed daily, is a ---Select--- a variable. In order to assess the effectiveness of taking large doses of vitamin C in reducing the duration of the common cold, researchers recruited 400 healthy volunteers from staff and students at a university. A quarter of the patients were assigned a placebo, and the rest were evenly divided between 1 9 Vitamin C, 3 9 Vitamin C, or 3 9 Vitamin C plus additives to be taken at onset of a cold for the following two days. All tablets had identical appearance and packaging. The nurses who handed the prescribed pills to the patients knew which patient received which treatment, but the researchers assessing the patients when they were sick did not. No signicant differences were observed in any measure of cold duration between the four groups, and the placebo group had the shortest duration of symptoms. (a) Was this an experiment or an observational study? Why? This was an ---Select--- , since the researchers --Select--- randomly assign different treatments to the participants. (b) What is the explanatory variable in this study? " number of days that participants received treatment ' ' amount of vitamic C taken by the participant " type of vitamin taken by the participant ' duration of the cold ' whether the participant got a cold What is the response variable in this study? ' number of days that participants received treatment amount of vitamin C taken by the participant " type of vitamin taken by the participant ' duration of the cold " whether the participant got a cold (c) Were the patients blinded to their treatment? ' ' Yes, because they did not know which treatment they were receiving. No, because they knew which treatment they were receiving. (c) Were the patients blinded to their treatment? ' ' Yes, because they did not know which treatment they were receiving. ' ' No, because they knew which treatment they were receiving. (d) Was this study double-blind? ' ' Yes, because neither the researchers nor the nurses knew which patients were receiving which treatments. ' No, the study was only partially double-blind because the nurses knew which patients were receiving each treatment. ' Yes, because the researchers did not know which patients were receiving which treatments. " No, because the patients knew which treatments they were receiving, and a study cannot be double-blind unless it is blind. (e) Participants are ultimately able to choose whether or not to use the pills prescribed to them. We might expect that not all of them will adhere and take their pills. Does this introduce a confounding variable to the study? Explain your reasoning. Since the patients were randomly assigned to the treatment groups and they ---Select-- blinded we would expect about an ---Select- number of patients in each group not to adhere to the treatment. Therefore, non-adherence 1-Select-: introduce a confounding variable to the study. Researchers collected data to examine the relationship between air pollutants and preterm births in Southern California. During the study, air pollution levels were measured by air quality monitoring stations. Specically, levels of carbon monoxide were recorded in parts per million, nitrogen dioxide and ozone in parts per hundred million, and coarse particulate matter (PMlo) in g /m3. Length of gestation data were collected on 143,196 births between the years 1989 and 1993, and air pollution exposure during gestation was calculated for each birth. The analysis suggested that increased ambient PM10 and, to a lesser degree, C0 concentrations may be associated with the occurrence of preterm births.1' (a) Identify the main research question of the study. What is the average length of gestation in Southern California? Are levels of carbon monoxide, nitrogen dioxide, ozone, and coarse particulate matter in Southern California too high? Is there an association between the levels of carbon monoxide, nitrogen dioxide, ozone, and coarse particulate matter in Southern California? \\ Is there an association between air pollution exposure and preterm births in Southern California? What are the average evels of carbon monoxide, nitrogen dioxide, ozone, and coarse particulate matter in Southern California? (b) Who are the subjects in this study? \\ The subjects are births in Southern California between 1989 and 1993. ' The subjects are parents of childern born in Southern California between 1989 and 1993. The subjects are all adults in Southern California between 1989 and 1993. The subjects are air pollution levels in Southern California between 1989 and 1993. ' The subjects are adults without childern in Southern California between 1989 and 1993. How many are included? (c) What are the variables in the study? (i) Identify the continuous numerical variables in this study. (Select all that apply.) carbon monoxide coarse particulate matter length of gestation ozone nitrogen dioxide ' age of parent _ There are no continuous numerical variables. (ii) Identify the discrete numerical variables in this study. (Select all that apply.) carbon monoxide coarse particulate matter length of gestation ozone nitrogen dioxide age of parent _ There are no discrete numerical variables. (iii) Identify the nominal categorical variables in this study. (Select all that apply.) carbon monoxide coarse particulate matter length of gestation ozone nitrogen dioxide age of parent There are no nominal categorical variables. (iv) Identify the ordinal categorical variables in this study. (Select all that apply.) ' carbon monoxide ' coarse particulate matter length of gestation ozone ' nitrogen dioxide ' age of parent There are no ordinal categorical variables. The Buteyko method is a shallow breathing technique developed by Konstantin Buteyko, a Russian doctor, in 1952. Anecdotal evidence suggests that the Buteyko method can reduce asthma symptoms and improve quality of life. In a scientific study to determine the effectiveness of this method, researchers recruited 600 adult asthma patients who relied on medication for asthma treatment. These patients were randomly split into two research groups: one practiced the Buteyko method and the other did not. Patients were scored on quality of life, activity, asthma symptoms, and medication reduction on a scale from very bad to very good. On average, the participants in the Buteyko group experienced a significant reduction in asthma symptoms and an improvement in quality of life. (a) Identify the main research question of the study. Do adult asthmatic patients rate their quality of life highly? Does the Buteyko method impact quality of life for asthmatic patients from Russia? Do adult asthmatic patients who practice the Buteyko method experience improvement in their condition? Do female asthmatic patients who practice the Buteyko method experience more or less improvement in their condition than male asthmatic patients who practice the Buteyko method? Do young (under age 18) and adult (over age 18) asthmatic patients respond differently to the Buteyko method? (b) who are the subjects in this study? The subjects are the adult patients using the Buteyko method. The subjects are the adult patients diagnosed and currently treated for asthma, and not using the Buteyko method. The subjects are the adult patients not using the Buteyko method. The subjects are are the adult patients diagnosed and currently treated for asthma, and using the Buteyko method. The subjects are the adult patients diagnosed and currently treated for asthma. How many are included? (c) What are the variables in the study? (i) Identify the continuous numerical variables in this study. (Select all that apply.) whether or not the patient practiced the Buteyko method age of patients gender of patients measures of quality of life, activity, asthma symptoms, and medication reduction There are no continuous numerical variables. (ii) Identify the discrete numerical variables in this study. (Select all that apply.) T whether or not the patient practiced the Buteyko method age of patients gender of patients measures of quality of life, activity, asthma symptoms, and medication reduction T There are no discrete numerical variables. (iii) Identify the nominal categorical variables in this study. (Select all that apply.) _ whether or not the patient practiced the Buteyko method age of patients gender of patients measures of quality of life, activity, asthma symptoms, and medication reduction There are no nominal categorical variables. (iv) Identify the ordinal categorical variables in this study. (Select all that apply.) whether or not the patient practiced the Buteyko method age of patients gender of patients measures of quality of life, activity, asthma symptoms, and medication reduction T There are no ordinal categorical variables. Researchers collected data to examine the relationship between air pollutants and preterm births in Southern California. During the study air pollution levels were measured by air quality monitoring stations. Suppose the length of gestation data were collected on 146,106 births between the years 1989 and 1993, and air pollution exposure during gestation was calculated for each birth. (a) Identify the population of interest in this study. all births in the US all births between 1989 and 1993 in Southern California ' all births between 1989 and 1993 in California all births between 1989 and 1993 in the US all births in Southern California Identify the sample in this study. The sample consists of births in the population of interest. (b) Comment on whether or not the results of the study can be generalized to the population, and if the ndings of the study can be used to establish causal relationships. If the births in this sample can be considered representative of all births in the population of interest, then the results ---Select--- 8 generalizable to the entire population of interest. Additionally, since the study is ---SeIecr--- B , the findings --Select--- be used to establish causal relationships. Researchers studying the relationship between honesty, age, and self-control conducted an experiment on 160 children between the ages of 5 and 15. The researchers asked each child to toss a fair coin in private and to record the outcome (white or black) on a paper sheet, and said they would only reward children who report white. Half the students were explicitly told not to cheat and the others were not given any explicit instructions. Differences were observed in the cheating rates in the instruction and no instruction groups, as well as some differences across children's characteristics within each group. (a) Identify the population of interest in this study. children between the ages of 5 and 15 currently enrolled in school ' children between the ages of 5 and 15 with a history of cheating ' children currently enrolled in school ' all children between the ages of 5 and 15 " children currently enrolled in school with a history of cheating Identify the sample in this study. The sample consists of children in the population of interest. (b) Comment on whether or not the results of the study can be generalized to the population, and if the ndings of the study can be used to establish causal relationships. If the children in this sample can be considered representative of all children in the population of interest, then the results ---Select--- 8 generalizable to the entire population of interest. Additionally, since the study is ---Select--- , the findings ---Select--- be used to establish causal relationships