2.4 Assessing reports
A report in The Sydney Morning Herald (Berry 2016) was entitled 'Aged cheese could help you age well'. Based on this headline:
- what are reasonable suggestions for the outcome and response variable?
- what are reasonable suggestions for the comparison and explanatory variable?
- would you expect the study to be observational or experimental? Explain.
Below is an extract from the newspaper article for the mice study that formed part of the research.
Cheese is not only delicious and nutritious, with its abundance in calcium and vitamin B12, it can also slow down the ageing process, according to a new study.
In the study published in the journal Nature Medicine, European researchers analysed the effect of a compound found in aged cheese (as well as legumes and whole grains) called spermidine [...] the team supplemented the drinking water of mice with spermidine. Control mice drank normal water.
They found that it "significantly extended" the [average] lifespan of the mice...
Based on this information:
- what are reasonable suggestions for the outcome and response variable for the mice study?
- what are reasonable suggestions for the comparison and explanatory variable?
- is the study observational or experimental? Explain.
- does the newspaper headline appear reasonable?
- why do the researchers give some mice plain drinking water?
Below is an extract from the newspaper article for the human study that formed part of the research.
... the researchers surveyed \(800\) Italians about their diet and found that those who reported a higher intake of spermidine had lower blood pressure and a \(40\) per cent lower risk of heart failure and other cardiovascular diseases.
Based on this information:
what are reasonable suggestions for the outcome and response variable for the human study?
what type of RQ is suggested: relational, correlational or repeated-measures?
is the study observational or experimental? Explain.
Are the following variables likely to be extraneous variables, confounding variables, or neither? Explain.
- The sex of the person.
- The number of siblings.
- The distance to the nearest hospital.
- The amount of exercise per week by the person.
- Whether their father had heart problems.
The newspaper article is based on a research paper (Eisenberg et al. 2016), in which the diets of more than \(800\) Italians were recorded in 1995, 2000 and 2005. From 1995 to 2010, the researchers recorded heart-related events for each subject: incidents of high blood pressure, heart failure, stroke and premature death from heart disease.
Those with the highest spermidine intakes had a \(40\)% lower risk of heart failure (both fatal and non-fatal) compared to those with the lowest spermidine intakes. Those with the highest spermidine intakes also had a significantly lower risk of any heart disease, compared to those with the lowest spermidine intakes.
- Does the newspaper headline appear consistent with the research article?
The study reports that the biggest contributor to spermidine intakes was wholemeal foods (accounting for \(13.4\)% of intake), apples and pears (\(13.3\)%), salad (\(9.8\)%), vegetable sprouts (\(7.3\)%) and potatoes (\(6.4\)%). Aged cheese appeared in the list in sixth place (\(2.9\)% of intake).
- Based on this information, do you agree with, or not agree with, the newspaper article headline? Explain.
- Is a cause-and-effect relationship reasonable? Explain.