Observational Studies and Experiments

To determine if carrot juice helps improve heart conditions, a juicing company asks a random sample of 100 adults about whether or not they drink carrot juice and their heart condition. The company finds an association between drinking carrot juice and healthy heart conditions. Which statement is true about a possible confounding variable?

A possible confounding variable is the amount of exercise. Those that drink carrot juice may be more concerned about their health and exercise more, which explains the healthy heart conditions.

Two study designs are described here. Which statement is a correct interpretation of the designs?

Design A is an observational study because store employees will just note what naturally occurred; Design B is not an observational study because coupons could influence guests.

A veterinarian selected a random sample of 10 dogs to study their sleep patterns. Five of the dogs were randomly assigned to eat dry dog food and the other five dogs were randomly assigned to eat wet dog food. The data showed that dogs who ate wet dog food were more likely to sleep regularly than those who ate dry dog food. Does this scenario describe an observational study or an experiment? This scenario describes an

Experiment

A nutritionist selected a random sample of adults and asked them about their eating and exercise habits. The data show that people who eat organic fruits and vegetables are more likely to exercise regularly than those who do not eat organic fruits and vegetables. Does this scenario describe an observational study or an experiment? This scenario describes an

Observational study

A vitamin company wants to evaluate whether its vitamins help to improve student energy levels. To conduct the experiment, the company randomly selects 100 college students and instructs them to eat healthy, have a full nights sleep, and take one vitamin each day for 6 months. Results showed an association between taking the vitamin and energy levels. Which of the following could be a potential confounding variable in the experiment? Select all that apply.

Sleep patterns Time spent exercising Quality of diet

A trucking company wants to evaluate whether a decrease in the weight of their trucks helps to increase gas mileage. The company randomly selects 100 of their truck drivers, driving trucks that are identical in every way other than weight, to monitor gas mileage over a 1-year period. Results showed an association between truck weight and gas mileage. Which is a possible confounding variable for the provided scenario?

The aggressiveness of the driver's driving style

At a rehab facility, physical therapists want to test the effectiveness of using a TENS unit on their patients with herniated disks. To conduct the experiment, the patients with herniated disks are randomly assigned to two groups: one using a TENS device and the other not using a TENS device. At the end of 8 weeks, the physical therapists compare the pain levels between the two groups.

The experimental unit in this experiment ✔ are subjects.

speed training service wants to explore the effectiveness of some of the classes offered to their clients. They randomly select 300 high school athletes and record their 50-meter dash time. The 300 high school athletes are then randomly assigned to three groups with 100 in each. One hundred athletes will take a circuit training class, 100 athletes will take an interval training class, and 100 athletes will take a plyometrics training class. At the end of 10 weeks of taking these classes, their 50-meter dash time will be recorded a second time. Their times will be analyzed to see which class showed the greatest overall improvement in times. Select all the sentences that correctly identify the components of the experiment.

The experimental units are subjects. There are three treatments. One treatment is a circuit training class. The factor is the type of class.

A test-prep service wants to explore the effectiveness of some of their offerings to their clients. They randomly select 75 high school juniors, who have each already taken the SAT test once, to participate in the experiment. The first group of 25 students will use study guides, the next group of 25 students will use online preparation courses, and the remaining group of 25 students will receive individual tutoring. At the end of 6 weeks of using these services, they will each take the SAT a second time. Their scores will be analyzed to see which group showed the greatest overall improvement in test scores. Select all the sentences that correctly identify the components of the experiment

The subjects are the 75 juniors. There are three treatments. One of the treatments is individual tutoring.

Medical researchers want to study the relationship between excessive exposure to radon gas and lung cancer. To conduct the study, the researchers select 40 adults between the ages of 45 and 50 that have been exposed to excessive amounts of radon gas through the cracked foundations of their homes. Results showed an association between excessive radon exposure and lung cancer. Complete the sentences to accurately describe the situation.

This is an example of a(n) experiment ✔ retrospective observational study A potential confounding variable in this experiment could be ✔ smoking The response variable, radon exposure ✔ may be influenced by more than just the explanatory variable, ✔ radon exposure

A researcher is interested in comparing five brands of acid reflux medications to see if one brand is better than the rest at relieving the symptoms of acid reflux, primarily heartburn. The 150 participants, who suffer from acid reflux, were randomly assigned to five different groups. Each group would receive one of the five brands of acid reflux medications. The improvement in heartburn of these 150 people is recorded and compared after 8 weeks of taking the medicine.

acid reflux medication, 5 different treatments or medications

In order to study the effects of caffeine on the resting heart rate, 20 adult volunteers were placed into two groups, and all of their heart rates were recorded. One group was given a caffeine pill, and the second group was given a sugar pill. After one hour, all of their heart rates were recorded again, and the changes in heart rates between the two groups were compared. Complete the sentences to accurately describe the situation.

caffeine pill, change in heart rate, sugar pill

Complete the statement about the design web. This design web represents a/an ______because the plants ____ subjected to treatments.

experiment, are

A researcher is interested in comparing five brands of acid reflux medications to see if one brand is better than the rest at relieving the primary symptom of acid reflux, heartburn. The 150 participants, who suffer from acid reflux, were randomly assigned to five different groups. Each group would receive one of the five brands of acid reflux medications. The improvement in heartburn of these 150 people is recorded and compared after 8 weeks of taking the medicine. Complete the sentences to accurately describe the situation.

five, acid reflux medications, 150 people in the study, are, subjects

Scenario A - In a famous study that began in 1948, a sample population in Framingham, Massachusetts, was selected and followed through the course of their lives. They were periodically tested to see if they had developed one of several types of heart disease. Scenario B - In a study of pregnant women, researchers reviewed medical histories and found that women who were diagnosed with gestational breast cancer were more likely to have their labor induced preterm than pregnant women who were not diagnosed. Complete the sentences by selecting the correct study type.

prospective, retrospective

Patients with ulcers in their upper intestines were placed into two groups; both groups had to swallow a deflated balloon with tubes attached. One group was given a treatment known as "gastric freezing," a process by which refrigerated liquid is pumped through their balloon for one hour in order to cool their stomach and relieve their ulcers. The second group had a body temperature liquid pumped through their balloon. Complete the sentences to accurately describe the situation. The treatment was the____ liquid. The placebo was the ____ liquid.

refrigerated, body temperature

In a study of more than 3,200 divorced couples, researchers from a therapist's office found that those couples where both partners had divorced parents were more than three times as likely to divorce than couples where both partners did not have divorced parents. Does this scenario describe a retrospective or prospective observational study?

retrospective

A pharmaceutical company is interested in comparing four brands of sleep medication to see which brand is best at relieving sleep pattern symptoms, primarily insomnia. The participants are 80 people with sleep pattern symptoms. They are randomly assigned to four groups of 20 participants. Each group receives one of the four brands of sleep medication. The improvement in the sleep pattern of the 80 participants is recorded 6 weeks after taking the medication and the average improvement is compared among the four treatment groups. What are the factor(s) and level(s) of this scenario?

sleep medication, 4 different treatments or medications

An insurance company is interested in comparing three options for anterior cruciate ligament (ACL) reconstruction to see if one option is better than the others. The participants are 60 people with an ACL tear. They are randomly divided into six groups. Each group receives one of the three options for ACL reconstruction (so that each treatment is given to two groups total). The functionality in leg motion of these 60 people is recorded and compared 12 weeks after surgery. Complete the sentences to accurately describe the situation.

three, options for ACL Reconstruction, 60 people in the study, are, subjects