LD LL Tumors 5 15 No Tumors 45 35 a. Determine the percentage of mice that developed tumors from each group (LL and LD). Compare them and comment. In the LD mice, % developed tumors. In the LL mice, % developed tumors. The LD mice developed tumors at b. Was this a controlled experiment or an observational study? How do you know? A. This was an observational study because there was a treatment and a control group. B. This was an observational study because there were two groups that were randomly assigned by the researc C. This was a controlled experiment because there were two groups that were randomly assigned by the resear D. This was a controlled experiment because there were more than 50 mice. c. Can we conclude that light for 24 hours a day causes an increase in tumors in mice? Why or why not? the LL mice. the same rate as a higher rate than a lower rate than b. Was this a controlled experiment or an observational study? How do you know? A. This was an observational study because there was a treatment and a control group. B. This was an observational study because there were two groups that were randomly assigned by the researchers. C. This was a controlled experiment because there were two groups that were randomly assigned by the researchers. D. This was a controlled experiment because there were more than 50 mice. c. Can we conclude that light for 24 hours a day causes an increase in tumors in mice? Why or why not? A. Because it was a controlled experiment, it can be concluded that light for 24 hours a day causes an increase in tumors in mice. B. This was a controlled experiment and a controlled experiment can never be used to infer causation. C. This was an observational study and an observational study can never be used to infer causation. D. Because it was an observational study, it can be concluded that light for 24 hours a day causes an increase in tumors in mice.