1.3 & 1.4 HW-Victor Maciel

1/9/26, 1:51 PM Student: _____________________ Date: _____________________ 1.3 & 1.4 HW-Victor Maciel Instructor: Victor Maciel Course: MTH.155.600.SP26 Assignment: 1.3 & 1.4 HW 1. What is​confounding? As an​example, explain how confounding might occur in this​study: A medical researcher chooses a group of middle school students for a study that seeks to measure the effectiveness of a behavioral treatment intended to help teenagers and young adults overcome a vaping habit. What is​confounding? A. Confounding is when the researchers and subjects in a study do not know who is in the treatment group and who is in the control group. B. Confounding is the mixing of effects from different factors so that the effects from the specific factors being studied cannot be determined. C. Confounding is the process of making a sample more representative of the population. D. Confounding is the process of eliminating all differences between the groups in a study so that the only difference that remains is the factor of interest to the researcher. How would confounding affect the study in the​example? A. If some of the teenagers are given the placebos and some are given the​treatment, a researcher would be certain that any differences between the two groups are attributable to the treatment. B. Confounding would make the results of the experiment more representative of the population. C. The researchers would be confounded as to whether the teenagers or the young adults are receiving the treatment. D. The middle school students may be subject to behavioral pressures​(due to their​ages) different from those of older teenagers or young​adults, so results for them may not be generally applicable to older groups. 2. What is a​placebo, and why is it important in an experiment to test the effectiveness of a​drug? What is a​placebo? A. A placebo refers to a situation in which a patient improves simply because they believe they are receiving a useful treatment. B. A placebo is physically similar to a​treatment, but it lacks any active​ingredients, so it should not by itself produce any effects. C. A placebo refers to any problem in the design or conduct of a statistical study that tends to favor certain results. D. A placebo refers to a specific member of a sample from which data are collected. Why is it important in an experiment to test the effectiveness of a​drug? A. A placebo exaggerates any psychological differences between the control group and the treatment group. B. A placebo makes the sample less representative of the population but the data can still be used to make inferences about the population. C. A placebo is important so that results from subjects given a treatment can be compared with the results from subjects given a placebo. D. A placebo makes the sample more representative of the population. https://tdx.acs.pearson.com/api/v1/print/highered 1/12 1/9/26, 1:51 PM 1.3 & 1.4 HW-Victor Maciel 3. What is​blinding, and why is it important in an experiment that is testing the effectiveness of a​drug? What is​blinding? A. Blinding is the practice whereby participants are kept in the dark and​can't see the test results. B. Blinding is the practice whereby participants and experimenters are separated by either a​one-way mirror​(single-blind) or by a wall​(double-blind). C. Blinding is the practice whereby participants​and/or experimenters do not know who belongs to the treatment group and who belongs to the control group. D. Blinding is the practice whereby participants​and/or experimenters do not know the effectiveness of the treatment. Why is blinding important in an experiment that is testing the effectiveness of a​drug? A. It is important to use blinding for participants so that they know that they are receiving the real​drug, and it is important to use it for experimenters so that they can evaluate results objectively based on who is getting the real drug. B. It is important to use blinding for participants so that they are not affected by the​drug, and it is important to use it for experimenters so that they can evaluate results objectively instead of being influenced by knowledge about who is getting the real drug. C. It is important to use blinding for participants so that they are not affected by the knowledge that they are receiving the real​drug, and it is important to use it for experimenters so that they can evaluate results objectively instead of being influenced by knowledge about who is getting the real drug. D. It is important to use blinding for participants so that they are not affected by the knowledge that they are receiving the real​drug, and it is important to use it for experimenters so that they​can't influence who is getting the real drug. 4. Determine whether the statement makes sense​(or is clearly​true) or does not make sense​(or is clearly​false). Explain clearly. I plan to use a​double-blind experiment to test the hypothesis that people will experience a decrease in their pulse rate if they exercise vigorously for 40 minutes every day. Choose the correct answer. A. The statement does not make sense. An experiment such as this cannot have a control group and so cannot be double blinded. B. The statement does not make sense. The subjects who exercise will know that they are exercising. C. The statement makes sense. By double blinding the​experiment, it will prevent any bias from the control group knowing what the experiment is about. D. The statement makes sense. By double blinding the​experiment, it will prevent any bias from the experimenters reviewing the result. https://tdx.acs.pearson.com/api/v1/print/highered 2/12 1/9/26, 1:51 PM 1.3 & 1.4 HW-Victor Maciel 5. Determine whether the following statement makes sense​(or is clearly​true) or does not make sense​(or is clearly​false). A psychologist suspects that breathing exercises can help people with depression. To decide whether he is​correct, he identifies a group of​subjects, watches them do the breathing exercises, and then asks them how they feel afterward. Select the correct choice below. A. The statement makes​sense, because asking how they feel is a good measure of depression. B. The statement makes​sense, because the psychologist set up an experiment to test his hypothesis. C. The statement does not make​sense, because asking how they feel is too imprecise for a study. D. The statement does not make​sense, because this experiment lacks a control group and also is subject to experimenter effects. 6. Determine whether the following study is an observational​study, an​experiment, or a​meta-analysis, and explain your choice. In a study of the effects of magnets on migraines​, some participants were treated with magnets while others were given​non-magnetic objects with a similar appearance. The magnets did appear to be effective in treating migraines. Choose the correct answer below. A. The study is an observational​study, because it is a retrospective study using data from the past. B. The study is a​meta-analysis, because an analysis of the data was used to determine effectiveness. C. The study is an experiment, because magnets are used. D. The study is an observational​study, because the participants were observed. E. The study is an experiment, because there is a treatment group and a control group. F. The study is a​meta-analysis, because the study was done on a group. 7. Determine whether the following study is an observational​study, an​experiment, or a​meta-analysis, and explain your choice. A study of 3,000 last year's cell phone contracts identified those with a text messaging plan and those without a text messaging plan. Choose the correct answer below. A. The study is an observational study because the data were collected all at once. B. The study is a​meta-analysis because an analysis of the data was used to determine effectiveness. C. The study is an experiment because a hypothesis is tested. D. The study is a​meta-analysis because the study was done on a group. E. The study is an experiment because there is a treatment group and a control group. F. The study is an observational study because there was no attempt to influence the results. https://tdx.acs.pearson.com/api/v1/print/highered 3/12 1/9/26, 1:51 PM 1.3 & 1.4 HW-Victor Maciel 8. Determine whether the study is an observational​study, an​experiment, or a​meta-analysis, and explain your choice. In a study of the XSORT gender selection method developed by the Genetics and IVF​Institute, 938 couples given treatment had 62 male babies and 876 female babies. Choose the correct answer. A. This study is a​meta-analysis because the researchers reviewed many past studies on the 62 male babies and the 876 female babies. B. This study is an observational study because the researchers observed the subjects without interfering. It is specifically a prospective study because the researchers set up to collect data in the future from the 62 male babies and the 876 female babies. C. This study is an observational study because the researchers observed the subjects without interfering. It is specifically a retrospective study because the researchers reviewed the official birth records of the 938 couples. D. This study is a​meta-analysis because the researchers reviewed many past studies on the 938 couples. E. This study is an experiment because the subjects were given a treatment. The treatment group consists of the 876 female babies given the XSORT treatment. The control group consist of the 62 male babies not given any treatment. F. This study is an experiment because the subjects were given a treatment. The treatment group consists of the 938 couples given the XSORT treatment. The control group consists of others not given any treatment. 9. Determine whether the following study is an observational​study, an​experiment, or a​meta-analysis, and explain your choice. Results were combined from eleven major studies involving a total of more than 2.45 million teenagers. The analysis confirmed that there is no linkage between video games and violence. Choose the correct answer below. A. The study is an observational study because it is a retrospective study using data from the past. B. The study is a​meta-analysis because an analysis of the data was used to determine effectiveness. C. The study is a​meta-analysis because the study was on a group of studies. D. The study is an experiment because there is a treatment group and a control group. E. The study is an observational study because the participants were observed. F. The study is an experiment because a hypothesis is tested. https://tdx.acs.pearson.com/api/v1/print/highered 4/12 1/9/26, 1:51 PM 1.3 & 1.4 HW-Victor Maciel 10. An experiment is designed to evaluate the effectiveness of irrigation and fertilizer on poplar tree health. Irrigation is used with one group of 60 poplar trees in a moist ​region, and fertilizer is used with 55 poplar trees in a dry region. The researchers doing the measurements of tree health are aware of which trees receive irrigation and which trees receive fertilizer. Identify any problems that are likely to cause confounding and explain how the problems could be avoided. Identify any problems that are likely to cause confounding. Select all that apply. A. There is likely to be some confounding in this study because the researchers making the tree measurements will be influenced by knowing which trees are receiving irrigation and which are receiving fertilizer. B. There is likely to be a placebo effect in this study because the subjects know whether they are receiving irrigation or fertilizer. C. The groups are so small that confounding is likely to be introduced by the selection of the group subjects. D. There is no control group. E. If there are differences in the health of the trees​, there is no way to know if the differences are attributable to the treatments ​(irrigation or fertilizer​) or to the type of region ​(dry or moist​). Explain how the problems could be avoided. Select all that apply. A. The size of the groups should be increased to eliminate the possibility of a biased sample. B. To isolate the effects of irrigation and fertilizer​, the researchers should add a control group of trees that does not receive irrigation or fertilizer. C. The​study's subjects should not be aware whether they receive irrigation or fertilizer. D. Differences in the health of the trees can be correctly attributed to irrigation​, fertilizer​, and region by using blocks of trees that receive irrigation and blocks of trees that receive fertilizer in both the moist and dry regions. E. The researchers doing the tree measurement should not be aware of which trees are receiving irrigation and which are receiving fertilizer. F. Either none of these methods could be used to avoid any problems or there were no problems to avoid. 11. What is peer​review? How is it​useful? Choose the correct answer below. A. Peer review is having experts in a field evaluate a research report before it is published. This lends credibility because it implies that other experts agree that the study was carried out properly. B. Peer review is having experts in a field evaluate a research report after it is published. It proves or disproves the validity of the study. C. Peer review is having experts in a field evaluate a research report before it is published. This guarantees that the study is valid. D. Peer review is having experts in a field evaluate a research report after it is published. This lends credibility as word of the study spreads among the experts in the field. https://tdx.acs.pearson.com/api/v1/print/highered 5/12 1/9/26, 1:51 PM 1.3 & 1.4 HW-Victor Maciel 12. Decide whether the statement below makes sense or does not make sense. Explain your choice. A pollster plans to improve survey results by only conducting polls in which the margin of error is zero. Choose the correct answer below. A. The statement does not make sense. A margin of error of zero implies that there is no uncertainty in a survey result. This could happen only if the entire population was​surveyed, rather than just a sample. B. The statement makes sense. A margin of error of zero implies that there is no uncertainty in a survey result. This could happen if the entire population was surveyed. C. The statement makes sense. Any value can be chosen for the margin of error. D. The statement does not make sense. The margin of error is always a fixed fraction of the sample statistic. 13. Decide whether the following statement makes sense​(or is clearly​true) or does not make sense​(or is clearly​false). Explain your reasoning. My experiment proved beyond a doubt that vitamin C can reduce the severity of​colds, because I controlled the experiment carefully for every possible confounding variable. Choose the correct answer below. A. The statement does not make sense because it is not always easy to discover confounding variables. B. The statement makes sense because every possible confounding variable can be eliminated through careful study. C. The statement makes sense because confounding variables are the only reason an​experiment's results could be doubted. D. The statement does not make sense because confounding variables would not affect the reliability of the experiment. https://tdx.acs.pearson.com/api/v1/print/highered 6/12 1/9/26, 1:51 PM 1.3 & 1.4 HW-Victor Maciel 14. A clothing company sponsored a survey showing that dressing stylishly is critically important for success in a job interview. Determine which of the eight guidelines for evaluating statistical studies appears to be most relevant. Explain your reasoning. 1 Click the icon to view the eight guidelines for critically evaluating a statistical study. Guideline (1) is most relevant because (2) 1: The Eight Guidlines The eight guidelines for critically evaluating a statistical study are given below. 1. Get a big picture view of the study. For​example, you should understand the goal of the​study, the population that was under​study, and whether the study was observational or an experiment. 2. Consider the source. In​particular, look for any potential biases on the part of the researchers. 3. Look for bias in the sample. That​is, decide whether the sampling method was likely to produce a representative sample. 4. Look for problems defining or measuring the variables of interest. Ambiguity in the variables can make it difficult to interpret reported results. 5. Beware of confounding variables. If the study neglected potential confounding​variables, its results may not be valid. 6. Consider the setting and wording in surveys. In​particular, look for anything that might tend to produce inaccurate or dishonest responses. 7. Check that results are presented fairly. For​example, check whether the study really supports the conclusions that are presented in the media. 8. Stand back and consider the conclusions. For​example, evaluate whether the study achieved its goals. If​so, do the conclusions make sense and have practical​significance? (1) (2) 5 7 4 6 3 2 8 1 the study is observational, not an experiment. the company can benefit from the survey results. "important" is not well defined and is difficult to measure. the survey could be worded to produce inaccurate responses. the sample is not likely to be representative of the population. https://tdx.acs.pearson.com/api/v1/print/highered 7/12 1/9/26, 1:51 PM 1.3 & 1.4 HW-Victor Maciel 15. In a study of​1,200 college​students, each was asked whether he or she was a good person. Determine which of the eight guidelines appears to be most relevant. Explain your reasoning. 2 Click the icon to view the eight guidelines for critically evaluating a statistical study. Choose the correct answer below. A. Guideline 4 is the most relevant.​"Good" is not well defined and is difficult to measure. B. Guideline 2 is the most relevant. There appears to be a potential bias on the part of the researchers to show that people do not consider themselves​"good." C. Guideline 3 is the most relevant. Since the sample was​self-selected there is a clear participation bias in this study. D. Guideline 7 is the most relevant. The results of the study do not seem to be reported fairly. 2: Eight Guidelines for Critically Evaluating a Statistical Study The eight guidelines for critically evaluating a statistical study are given below. 1. Get a big picture view of the study. For​example, you should understand the goal of the​study, the population that was under​study, and whether the study was observational or an experiment. 2. Consider the source. In​particular, look for any potential biases on the part of the researchers. 3. Look for bias in the sample. That​is, decide whether the sampling method was likely to produce a representative sample. 4. Look for problems defining or measuring the variables of interest. Ambiguity in the variables can make it difficult to interpret reported results. 5. Beware of confounding variables. If the study neglected potential confounding​variables, its results may not be valid. 6. Consider the setting and wording in surveys. In​particular, look for anything that might tend to produce inaccurate or dishonest responses. 7. Check that results are presented fairly. For​example, check whether the study really supports the conclusions that are presented in the media. 8. Stand back and consider the conclusions. For​example, evaluate whether study achieved its goals. If​so, do the conclusions make sense and have practical​significance? https://tdx.acs.pearson.com/api/v1/print/highered 8/12 1/9/26, 1:51 PM 1.3 & 1.4 HW-Victor Maciel 16. An independent research firm is attempting to figure out for themselves whether there is too much violence in movies. The firm conducts a survey of adults who view movies. Each interview subject is asked this​question: "Is there too much violence in​movies?" Determine which of the eight guidelines for evaluating statistical studies appears to be most relevant. Explain your reasoning. 3 Click the icon to view the eight guidelines for critically evaluating a statistical study. Guideline (1) is most relevant because (2) 3: The Eight Guidlines The eight guidelines for critically evaluating a statistical study are given. 1. Get a big picture view of the study. For​example, you should understand the goal of the​study, the population that was under​study, and whether the study was observational or an experiment. 2. Consider the source. In​particular, look for any potential biases on the part of the researchers. 3. Look for bias in the sample. That​is, decide whether the sampling method was likely to produce a representative sample. 4. Look for problems defining or measuring the variables of interest. Ambiguity in the variables can make it difficult to interpret reported results. 5. Beware of confounding variables. If the study neglected potential confounding​variables, its results may not be valid. 6. Consider the setting and wording in surveys. In​particular, look for anything that might tend to produce inaccurate or dishonest responses. 7. Check that results are presented fairly. For​example, check whether the study really supports the conclusions that are presented in the media. 8. Stand back and consider the conclusions. For​example, evaluate whether the study achieved its goals. If​so, do the conclusions make sense and have practical​significance? (1) (2) 6 3 8 4 7 2 1 5 "too much" is not well defined and is difficult to measure. the question is worded to produce inaccurate responses. the firm can benefit from the survey results. the study is observational, not an experiment. the sample is not likely to be representative of the population. 17. An article noted that chocolate is rich in flavonoids. The article reports that​"regular consumption of foods rich in flavonoids may reduce the risk of coronary heart​disease." The study received funding from a candy company and a chocolate manufacturers association. Identify and explain at least one source of bias in the study described. Then suggest how the bias might have been avoided. Choose the correct answer below. A. The data do not seem to support the claims being made by the article. The​article's author should consult an expert to make sure that he or she is correctly interpreting the​study's results. B. The questions used in the study might have caused the respondents to give inaccurate or dishonest responses. The question wording should be changed to be more neutral. C. Since the sample is​self-selected, there is a definite participation bias in this study. The researchers should randomly select the subjects of the study. D. The researchers may have been more inclined to provide favorable results because funding was provided by a party with a definite interest. The bias could have been avoided if the researchers were not paid by the candy company and the chocolate manufacturers. https://tdx.acs.pearson.com/api/v1/print/highered 9/12 1/9/26, 1:51 PM 1.3 & 1.4 HW-Victor Maciel 18. When author Shere Hite wrote Women and​Love: A Cultural Revolution in Progress​, she based conclusions about the general population of all women on 4500 replies that she received after mailing 100,000 questionnaires to various​women's groups. Identify and explain a source of bias in this study. Then suggest how the bias might have been avoided. Identify and explain a source of bias in this study. Choose the correct answer. A. Returning the questionnaires was voluntary. B. The author wrote the questionnaires. C. The questionnaires were only sent to women. D. An insufficient number of questionnaires were sent. Suggest how the bias might have been avoided. Select all that apply. A. The author could have interviewed a randomly selected sample of women. B. The author could have mailed more questionnaires. C. The author could have mailed questionnaires to men and women. D. The author could have hired a​women's group to conduct the survey. https://tdx.acs.pearson.com/api/v1/print/highered 10/12 1/9/26, 1:51 PM 1.3 & 1.4 HW-Victor Maciel 1. B. Confounding is the mixing of effects from different factors so that the effects from the specific factors being studied cannot be determined. D. The middle school students may be subject to behavioral pressures​(due to their​ages) different from those of older teenagers or young​adults, so results for them may not be generally applicable to older groups. 2. B. A placebo is physically similar to a​treatment, but it lacks any active​ingredients, so it should not by itself produce any effects. C. A placebo is important so that results from subjects given a treatment can be compared with the results from subjects given a placebo. 3. C. Blinding is the practice whereby participants​and/or experimenters do not know who belongs to the treatment group and who belongs to the control group. C. It is important to use blinding for participants so that they are not affected by the knowledge that they are receiving the real​drug, and it is important to use it for experimenters so that they can evaluate results objectively instead of being influenced by knowledge about who is getting the real drug. 4. B. The statement does not make sense. The subjects who exercise will know that they are exercising. 5. D. The statement does not make​sense, because this experiment lacks a control group and also is subject to experimenter effects. 6. E. The study is an​experiment, because there is a treatment group and a control group. 7. F. The study is an observational study because there was no attempt to influence the results. 8. F. This study is an experiment because the subjects were given a treatment. The treatment group consists of the 938 couples given the XSORT treatment. The control group consists of others not given any treatment. 9. C. The study is a​meta-analysis because the study was on a group of studies. 10. A. There is likely to be some confounding in this study because the researchers making the tree measurements will be influenced by knowing which trees are receiving irrigation and which are receiving fertilizer. , D. There is no control group., E. If there are differences in the health of the trees​, there is no way to know if the differences are attributable to the treatments (irrigation or fertilizer​) or to the type of region ​(dry or moist​). B. To isolate the effects of irrigation and fertilizer​, the researchers should add a control group of trees that does not receive irrigation or fertilizer. , D. Differences in the health of the trees can be correctly attributed to irrigation​, fertilizer​, and region by using blocks of trees that receive irrigation and blocks of trees that receive fertilizer in both the moist and dry regions. , E. The researchers doing the tree measurement should not be aware of which trees are receiving irrigation and which are receiving fertilizer. https://tdx.acs.pearson.com/api/v1/print/highered 11/12 1/9/26, 1:51 PM 1.3 & 1.4 HW-Victor Maciel 11. A. Peer review is having experts in a field evaluate a research report before it is published. This lends credibility because it implies that other experts agree that the study was carried out properly. 12. A. The statement does not make sense. A margin of error of zero implies that there is no uncertainty in a survey result. This could happen only if the entire population was​surveyed, rather than just a sample. 13. A. The statement does not make sense because it is not always easy to discover confounding variables. 14. (1) 2 (2) the company can benefit from the survey results. 15. A. Guideline 4 is the most relevant.​"Good" is not well defined and is difficult to measure. 16. (1) 4 (2) "too much" is not well defined and is difficult to measure. 17. D. The researchers may have been more inclined to provide favorable results because funding was provided by a party with a definite interest. The bias could have been avoided if the researchers were not paid by the candy company and the chocolate manufacturers. 18. A. Returning the questionnaires was voluntary. A. The author could have interviewed a randomly selected sample of women. https://tdx.acs.pearson.com/api/v1/print/highered 12/12