Absolute and relative risk

Khatia organises two different training courses, Course A and Course B, to help people to learn to type. She wants to compare the two different courses to see which is better. At the end of each course the people are given a skills test.

The table shows the number of participants who passed and failed the skills test for each of the two courses.

Find the relative risk of failing the skills test having taken Course A compared to Course B.

Give an interpretation of your answer to part (a).

Khatia organises two different training courses, Course A and Course B, to help people to learn to type. She wants to compare the two different courses to see which is better. At the end of each course the people are given a skills test.

The table shows the number of participants who passed and failed the skills test for each of the two courses.

Find the relative risk of failing the skills test having taken Course A compared to Course B.

Give an interpretation of your answer to part (a).

The table gives, for the Isle of Skye, the number of days with rainfall during the 30 days of April 2019 and during the 30 days of June 2019

Use the information in the table to find the absolute risk of rainfall for a day in April.

Use the information in the table to work out an estimate for the relative risk of rainfall for any June day compared with any April day.

Glen plans to visit the Isle of Skye next year, in either June or July.

The relative risk of rainfall for any July day compared with any June day is 0.8

He does not want it to rain when he visits.

Glen decides to go in July instead of June.

Explain how the relative risk of 0.8 could be used to justify Glen’s decision.

Tomasz found information about the weather on the Isle of Skye for the 31 days of May 2019 and the 31 days of July 2019

The table gives, for the Isle of Skye, some information about the number of days with rainfall during May.

Using the information in the table, find the number of days with rainfall in May 2019 You must show your working.

The relative risk of rainfall for a day in July compared with a day in May is 1.29

Find the number of days with rainfall in July 2019 You must show your working.

Emma asks each person in a group of people on the second day of their summer holiday whether they wear sunblock and whether they have sunburn.

The table gives information about their answers.

Find the relative risk of a person who does wear sunblock having sunburn, compared with a person who does not wear sunblock having sunburn.

Give an interpretation of your answer to part (a).

Emma also collects information from this group of people about whether they drink the tap water and whether they have had upset stomachs.

She works out the relative risk of a person who drinks the tap water having an upset stomach, compared with a person who does not drink the tap water having an upset stomach. She gets a value of 1

Give an interpretation of this relative risk with the value of 1

The manager of a garage records optional extra features sold with each new car sold last month. The optional extra features are air conditioning (A), bluetooth (B) and sat nav (S).

Last month, 80 cars were sold 7 cars were sold with sat nav and bluetooth and air conditioning 15 cars were sold with sat nav and bluetooth only 21 cars were sold with sat nav and air conditioning only 10 cars were sold with bluetooth and air conditioning only 8 cars were sold with sat nav only 33 cars in total were sold with bluetooth 44 cars in total were sold with air conditioning.

Complete the Venn diagram using this information.

Inge picks at random a car that was sold last month.

She thinks that the probability that the car has bluetooth given that it has sat nav is greater than the probability that the car has bluetooth given that it has not got sat nav.

Is Inge correct? You must show your working.

Second-hand cars are also sold at the garage. The manager records whether the second-hand cars have a full service history or not. She also records whether each second-hand car has a breakdown or not in the first year after being sold.

The table gives information about the second-hand cars sold at the garage in 2018

Paul says that the relative risk of a second-hand car without a full service history having a breakdown in the first year after being sold, compared with a second-hand car with a full service history having a breakdown in the first year after being sold, is 2

Show that Paul is correct.

Interpret a relative risk of 2 in this context.