Presentation on theme: "Eating PCBs from Lake Ontario: A Clicker Case on Science and the Media"— Presentation transcript:
1 Eating PCBs from Lake Ontario: A Clicker Case on Science and the Media Eric Ribbens, Western Illinois University
2 JillJill wiped away a tear as she sat down on the couch. The home pregnancy kit she had just used clearly indicated that she was not pregnant.“Why?” she wondered. “I just want a baby!”Jill and Steve had been trying to get pregnant for over three years now without success.
3 She turned on the radio… The announcer’s voice boomed out:“Do fish from Lake Ontario prevent pregnancy? Study says yes! Women who eat fish from Lake Ontario are more likely to have menstruation problems, take longer to get pregnant, and may have altered levels of estrogen. So, if you forgot to take the pill... just eat some fish!”
4 The announcer moved on to another topic, after cracking a joke about how fishermen were going to disappear because they couldn’t have babies.Jill began to cry. It was those fish, it had to be those fish. She was going to dig through the freezer, throw all the fish away, and break Steve’s fishing rods! She stormed into their bedroom and collapsed on their bed, sobbing.
5 SteveSteve ambled into the bedroom from the bathroom, where he had been shaving, to find Jill sobbing on the bed.“What’s wrong, honey?” he asked, cuddling her. In between sobs, Jill told him what the radio announcer had said.
6 Another Perspective“That doesn’t sound right”, Steve thought. He grabbed his bedside copy of the Lake Ontario Sport Fisherman magazine and flipped throughto a page summarizing recent news related to the Great Lakes. “Isn’t this the same study?” Steve thought? He read:
7 Another Study Proves Lake Ontario Fish Are Safe To Eat “Not only is it a great thrill to catch a big fish out of Lake Ontario, but now scientists have also shown the fish really are safe to eat. Some environmentalists have been worryingthat PCB contamination in Lake Ontario might get into the big finnies. Although PCBs are some of the most stable chemicals around, some people worry that they might affect reproduction.”
8 Lake Ontario Fish Safe“Even though PCB levels in Lake Ontario have been decreasing, some UB researchers tracked women who eat fish from the lake. And the news is indeed reassuring. Menstrual cycles were a mere 12 hours shorter, and the amount of fish ingested had no significant effect on the time it took to become pregnant.So ladies, get your spatula out! These fish are fun to catch... and good to eat!”
9 Steve read the article to Jill Steve read the article to Jill. After hearing it, Jill was completely confused. Which story was right? She picked up the phone and dialed her best friend’s number. Laura was a nurse who worked for a pediatrician. They had gone to school together, dated together, and now they exercised together and dreamed of children together.“Laura!” Jill cried. “Did you hear that maybe I can’t get pregnant because of those fish Steve keeps catching!” Laura firmly replied: “Calm down Jill, and tell me the whole story. I read about that study too, and it doesn’t sound that bad to me!”
10 Three VersionsGet together in small groups and quickly decide (each version is on the handout):What the radio broadcast says?What the magazine article says?What the news release says?Think in terms of the three people: Jill (trying to get pregnant), Steve (Jill’s husband), Laura (Jill’s friend).
11 What Should Laura Do?Imagine you are Laura. Jill is coming over, and you need to explain this to her and help her figure out what to do. What would you say? In particular, does this study really show that Jill’s problems with getting pregnant could be due to the fish she eats?
12 CQ#1: What would you tell Jill? PCBs in the fish she ate are preventing her from getting pregnant.It’s safe to eat fish out of Lake Ontario.You can’t tell whether it’s safe or not.It may be unsafe, but the news story is vague.
13 In small groupsWhat was the research question for the study headed by Germaine Buck?What was the research question for the study headed by Pauline Mendola?
14 CQ#2: Both of these studies were interested in: Women’s reproductive health.Showing fish in Lake Ontario are dangerous to eat.How many PCBs are in Lake Ontario fish.Why fishermen don’t have many children.
15 Research Question Dr. Buck: Effects of PCBs on the time it takes to get pregnant.Dr. Mendola:Effects of PCBs on menstrual cycles.Both studies used the New York Angler Cohort.
16 In small groupsWhat questions do you think they asked the participants in the time-to-pregnancy study? Describe the data collected by this study.What questions do you think they asked participants in the menstrual cycle study?
17 CQ#3: One big problem with Dr. Buck’s study is: Expecting women to remember how long they have eaten fish from Lake Ontario.Expecting women to remember how long they have been trying to get pregnant.Assuming that if you are not on birth control then you are trying to get pregnant.They didn’t ask any questions of the men.
18 CQ#4: One big problem with Dr. Mendola’s study is: Women will think the questions were intrusive and won’t answer honestly.It didn’t randomly assign women to eat fish vs. no fish.The researchers didn’t ask how many fish these women ate.It’s unclear how precise women were expected to be: Hours? Days? Weeks?
19 Dr. Buck’s Study 874 women trying to get pregnant. Telephone interviews:Trying to become pregnant? Did you?If so, how many cycles before becoming pregnant? (If not, then what???)Fish consumption data:Do you eat Lake Ontario fish?How many years have you eaten Lake Ontario fish?
20 Dr. Mendola’s Study 2,223 women, Survey data: Fish consumption data: Length of menstrual cycle,Regularity of menstrual cycle,Fish consumption data:Do you eat Lake Ontario fish?How many years?
21 Look at the statistical significances reported: Dr. Buck’s study: “Researchers found a small conception delay for women who ate fish, but the effect was not statistically significant.”Dr. Mendola’s study: Nothing reported (the wording “results” implies statistical significance?).
22 CQ#5: What does it mean when someone says an effect is statistically insignificant? There is a good chance the effect doesn’t really exist, based on your data.Your data is wrong, and you need to redo your experiment.Your hypothesis was written poorly. Go back to the hypothesis and redesign the project.
23 CQ#6: What kind of study were these? ComparativeControlledCan’t tell
24 Types of Experimental Designs ControlledSet up experiment. Don’t let anything vary except the parameter you are studyingMeasure resulting “things.” Compare results to predicted results from hypothesis.ComparativeFind a set of comparable things already in existence.Measure existing things. Compare results to predicted results from hypothesis.
25 Small group workThis was a comparative study, not a controlled study. What are the advantages of the controlled approach as compared to the comparative approach? What are the disadvantages?
26 In small groupsWhat did the researchers determine about the relationship between PCB consumption and the amount of time it takes to become pregnant?
27 CQ#7: Women who ate fish… Are less likely to get pregnant.Take longer to get pregnant.Get pregnant more quickly.Don’t seem to be affected.Are more likely to have twins.
28 In small groupsWhat did the researchers determine about the relationship between PCB consumption and the menstrual cycle?
29 Menstrual Cycle Results 1.1 days shorter if eat fish >1x / month.1.3 days shorter if eat lots of fish.0.5 days shorter for both if regular menstrual cycles.
30 CQ#8: Was the radio description valid? Yes, the radio broadcast got the story right.No, the radio broadcast got the story wrong.We can’t tell.
31 CQ#9: Was the magazine description valid? Yes, the magazine got the story right.No, the magazine got the story wrong.We can’t tell.
32 CQ#10: Was the news release valid? Yes, the news release got the story right.No, the news release got the story wrong.We can’t tell.
33 In small groupsThe researchers didn’t find all that much, so why did they do it? Isn’t it a colossal waste of money to investigate something and not get decent results?
34 CQ#11: If you think the researchers didn’t find all that much, why did they do it? Isn’t it a colossal waste of money to investigate something and not get decent results?It is a big waste of time: NSF shouldn’t fund research that doesn’t produce significant results.That’s how research goes: you don’t know the results before you do them, and results of no effect also tell us something about the hypothesis.
35 In small groupsWhat should Jill do? What would you do if you were Jill? (Yes, I know you guys don’t plan to get pregnant … so what would you want your wife to do?)