Unit 7 Day 7 Observational Study vs Experimental Study

For each question categorize the study as either an Observational Study or an Experimental Study.

Remember: 
Observational Study: Researchers don’t assign choices; they simply observe them.
Experimental Study (Experiment): Researchers assign subjects to different treatments.  An experiment requires a random assignment of subjects to treatments.

6

Categorize the studies:

The leg muscles of men aged 60 to 75 were 50% to 80% stronger after they participated in a 16‐week, high‐intensity resistance‐training program twice a week. (Journal of Gerontology 55A [2000}: B336)
Among a group of disabled women aged 65 and older who were tracked for several years, those who had a vitamin B12 deficiency were twice as likely to suffer severe depression as those who did not. (American Journal of Psychology 157 [2000]: 715)
Over a 4‐month period, among 30 people with bipolar disorder, patients who were given a high dose (10g/day) of omega‐3 fats from fish oil improved more than those given a placebo. (Archives of General Psychiatry 56 [1999]: 407)

Observational Study
Experiment

6

Categorize the studies:

Some gardeners prefer to use nonchemical methods to control insect pests in their gardens. Researchers have designed two kinds of traps, and want to know which design will be more effective. They randomly choose 10 locations in a large garden and place one of each kind of trap at each location. After a week, they count the number of bugs in each trap.
In 2001 a report in the Journal of the American Cancer Institute indicated that women who work at nights have a 60% greater risk of developing breast cancer. Researchers based these findings on the work histories of 763 women with breast cancer and 741 women without the disease.
In 2002, the journal Science reported that a study of women in Finland indicated that having sons shortened the lifespan of mothers by about 34 weeks per son, but that daughters helped to lengthen the mothers’ lives. The data came from church records from the period 1640 to 1870.

Experimental Study
Observational Study

6

Categorize the following studies (all are observational) as Retrospective or Prospective:

A group of disabled women aged 65 and older were tracked for several years, those who had a vitamin B12 deficiency were twice as likely to suffer severe depression as those who did not. (American Journal of Psychology 157 [2000]: 715)
The leg muscles of men aged 60 to 75 were measured at the beginning of a study. The leg muscles were found to be 50% to 80% stronger after they participated in a 16‐week, high‐intensity resistance‐training program twice a week. (Journal of Gerontology 55A [2000}: B336)
A recent study in Europe looked at a large group of women of childbearing age. The researchers asked each woman how much alcohol they had consumed over the past 12 months. The researchers found that women who drank moderate amounts of alcohol were somewhat less likely to have infertility than women who did not. (November, 2001).

Restrospective Observational Study
Prospective Observational Study

6

What are the three principle of Experimental Design?

Select all three:

4

Some gardeners prefer to use nonchemical methods to control insect pests in their gardens. Researchers have designed two kinds of traps, and want to know which design will be more effective. They randomly choose 10 locations in a large garden and place one of each kind of trap at each location. After a week, they count the number of bugs in each trap.

How many treatments are in this experiment?

4

Some people who race greyhounds give the dogs large doses of Vitamin C in the belief that the dogs will run faster. Investigators at the University of Florida tried three different diets in random order on each of five racing greyhounds. They were surprised to find that when the dogs ate high amounts of Vitamin C they ran more slowly.

How many treatments are in the experimental study?

4

Some people who race greyhounds give the dogs large doses of Vitamin C in the belief that the dogs will run faster. Investigators at the University of Florida tried three different diets in random order on each of five racing greyhounds. They were surprised to find that when the dogs ate high amounts of Vitamin C they ran more slowly.

Using the information provided, what are the different treatments in the experimental study?

4

Some people who race greyhounds give the dogs large doses of Vitamin C in the belief that the dogs will run faster. Investigators at the University of Florida tried three different diets in random order on each of five racing greyhounds. They were surprised to find that when the dogs ate high amounts of Vitamin C they ran more slowly.

Was control used in this experimental study?

4

After menopause some women take supplemental estrogen. There is concern that if these women also drink alcohol their estrogen levels will rise too high.
12 volunteers who were receiving supplemental estrogen were randomly divided into 2 groups, as were 12 additional volunteers who were not receiving estrogen.
In each case, one group drank an alcoholic beverage, the other non-alcoholic.
An hour later everyone’s estrogen level was measured. Only those on supplemental estrogen showed a marked increase.

How many treatment groups does this experimental study involve?

8

After menopause some women take supplemental estrogen. There is concern that if these women also drink alcohol their estrogen levels will rise too high.

12 volunteers who were receiving supplemental estrogen were randomly divided into 2 groups, as were 12 additional volunteers who were not receiving estrogen.

In each case, one group drank an alcoholic beverage, the other non-alcoholic.

An hour later everyone’s estrogen level was measured. Only those on supplemental estrogen showed a marked increase.

Select the treatment groups in this experimental study,
there should be four groups.

4

Unit 7 Day 7 Observational Study vs Experimental Study

Categorize the studies:

Categorize the studies:

Categorize the following studies (all are observational) as Retrospective or Prospective:

What are the three principle of Experimental Design?

Select all three:

Explain how blinding could have been used in the study described in #10 to prevent bias in the results recorded by the researchers.

Categorize the studies:

Categorize the studies:

Categorize the following studies (all are observational) as Retrospective or Prospective:

What are the three principle of Experimental Design?

Select all three:

Explain how blinding could have been used in the study described in #10 to prevent bias in the results recorded by the researchers.

Unit 7 Day 7 Observational Study vs Experimental Study

Unit 7 Day 7 Observational Study vs Experimental Study

Categorize the studies:

Categorize the studies:

Categorize the following studies (all are observational) as Retrospective or Prospective:

What are the three principle of Experimental Design?Select all three:

Explain how blinding could have been used in the study described in #10 to prevent bias in the results recorded by the researchers.

Categorize the studies:

Categorize the studies:

Categorize the following studies (all are observational) as Retrospective or Prospective:

What are the three principle of Experimental Design?Select all three:

Explain how blinding could have been used in the study described in #10 to prevent bias in the results recorded by the researchers.

What are the three principle of Experimental Design?

Select all three:

What are the three principle of Experimental Design?

Select all three: