Statistics Basics
What is Data?
Information that has been collected.
What is a population in statistics?
The whole group being studied.
What type of data uses groups or categories?
Categorical data
What is the mode?
The result that appears most often.
What does frequency mean?
How many times a result appears.
Is this primary or secondary data? A student surveys 20 classmates about their favourite sport.
Primary data
What is a sample in statistics?
A smaller group chosen from the population.
What type of data is “number of pets”?
Discrete numerical data
Find the mode: 4, 5, 5, 6, 7.
5
If 7 students chose soccer, what is the frequency for soccer?
7
Is this primary or secondary data? A student uses AFL ladder results from a website. Explain why.
Secondary data, because someone else collected/published it.
A student asks 10 Year 8 students about recess. What is the sample?
The 10 Year 8 students asked.
What type of data is “time taken to run 100 metres”?
Continuous numerical data
Find the range: 3, 8, 10, 4, 12.
9
In a dot plot, if “Comedy” has 5 dots above it, what does that mean?
5 people chose comedy.
A student wants to know the most popular movie genre in Year 8. Give one way they could collect primary data.
Survey/interview Year 8 students.
A student wants to know what all students at the school think about the canteen. They only ask their friends. Why is this sample weak?
It is biased/not representative because friends may have similar opinions.
Classify both: favourite music genre and number of siblings.
Favourite music genre = categorical. Number of siblings = discrete numerical.
Find the range and mode: 2, 6, 6, 9, 10, 6, 4.
Range = 8, Mode = 6
Results: Dog, Cat, Dog, Bird, Dog, Cat. What is the mode?
Dog
A student uses TikTok comments to decide what all teenagers think about school uniforms. What is one problem with this data source?
It may be biased/not representative/only includes certain people.
A student wants to know the favourite sport of Year 8 students. Which is better: asking 5 friends or randomly asking 30 Year 8 students? Explain why.
Randomly asking 30 Year 8 students, because it is larger and more representative.
A survey question asks, “How much do you like maths from 1 to 5?” Is this categorical, discrete numerical, or continuous numerical? Explain.
Discrete numerical, because the answers are fixed numbers: 1, 2, 3, 4, 5.
Find the mode: 2, 2, 3, 3, 4, 5. What is special about this data set?
Modes = 2 and 3. It is bimodal.
Results: Red, Blue, Red, Green, Blue, Blue, Red. Create the frequency counts and identify the mode.
Red = 3, Blue = 3, Green = 1. Modes = Red and Blue.