Can We Believe the Claims

Can we believe the claims?

Aims

In this activity you will be presented with some data from a scientist who is working for a company making a spread. The company claims that the spread reduces blood cholesterol. You will need to answer some questions about whether you feel the data is valid and if not, why. You will need to consider how the scientist could test the claim to make it more repeatable and reproducible.

Method

1 Read the following information and then answer the questions that follow:

High levels of cholesterol in your blood seem to increase the risk of getting heart disease. Heart disease is one of the main causes of death in the UK and USA. Levels of cholesterol below 5.0 mmol/l are considered normal.

A company called “Happy Heart” wanted to promote their new spread which they claim reduces blood cholesterol. They paid a scientist, Mr White, to do a study which they could use in their advertising.

Mr White recruited 30 volunteers, all of whom had blood cholesterol levels over 6.5mmol/l. He asked half the group to use the spread twice a day as part of their diet, e.g. on bread or a jacket potato. The other half of the group were asked to use butter instead of their usual spread. The study lasted for three months and he agreed to pay them at the end if they followed his instructions.

After three months, the cholesterol levels in both groups were measured. Mr White stated that in the group using the spread, cholesterol levels were reduced to below 5.5mmol/l. In the group using butter there were mixed results, some lowered, some stayed the same and some were raised. It was also discovered that four members of the group using the spread had just started to take statins.

A different scientist who is well known and respected in this field said that there were many flaws in this study and it should not be believed.

Questions

1 What aspects of this study fail to produce results that are repeatable and reproducible?

……………………………………………………………………………………………………....

2 What factors have not been controlled in this study, bringing the validity of the research into question?

3 Why might Mr White be biased?

……………………………………………………………………………………………………....

4 Why could information given by the volunteers be unreliable?

5 What piece of information given in the text makes the results of the group who used the spread flawed?

6 How would you change this study to make the data more repeatable and reproducible?