Compare modes, ranges and distribution shapes; critique claims and plan fair data collection.
Free examples and worked answers. No account needed.
Practise the method.
Compare modes, ranges and distribution shapes; critique claims and plan fair data collection.
Compare modes, ranges and distribution shapes; critique claims and plan fair data collection.
Example 1
Ratings run from 1= very dissatisfied to 5= very satisfied. Which comparison best describes the two distributions?
Satisfaction ratings: ordinal categories
Rating
Group A
Group B
1
1
6
2
2
5
3
2
2
4
5
2
5
6
1
Show worked answer
Answer: A is concentrated at higher ratings; B is concentrated at lower ratings.
Satisfaction ratings are ordinal categories with a meaningful order.
A has most responses at 4 and 5; B has most at 1 and 2. The distribution for A is shifted toward greater satisfaction.
Example 2
A class surveyed all its 19 students: 13 preferred starting sport before lunch and 6 preferred after lunch. Which statement is supported by this investigation?
Show worked answer
Answer: More students in this class preferred sport before lunch.
13 is greater than 6, so before lunch was preferred more often in the surveyed class.
The evidence concerns this class's preferences. It does not establish results for every class or a causal effect on performance.
Example 3
A school newsletter claims “Most students want more football.” Its evidence is a survey of only the football club. What is the main weakness?
Show worked answer
Answer: The surveyed group may not represent all students.
Football club members are likely to have different interests from some other students.
To make a school-wide claim, collect relevant responses from a sample that better represents the whole school.
Put it into practice.
Sign in to choose a set, get feedback and keep your progress.