Science Unit 4, Data Science 2 ~25 min Checkpoint 3

Checkpoint 3

Review the key ideas from Lessons 11-15, then test yourself with 10 multiple-choice questions and 3 short-answer questions.

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Quick Review

Using a Large Dataset to Develop and Test a Question

Focus: Secondary data is collected by someone else, such as the Bureau of Meteorology or the ABS, and reused. The workflow is to explore the data, notice a pattern, write an investigable question that matches the columns you have, identify the independent and dependent variables, clean the data, then analyse it. A question can only ask about columns the dataset actually contains.

Key terms: Secondary data, Cleaning data, Investigable question

Descriptive Analysis and Descriptive Statistics

Focus: Descriptive statistics summarise the data you have. The mean is the sum of values divided by how many there are, the median is the middle value once the data is in order, and the mode is the most common value. The range (highest minus lowest) measures spread. The median is more reliable than the mean when there are outliers.

Key terms: Mean, Median, Mode, Range

Univariate and Bivariate Analysis

Focus: Univariate analysis describes one variable on its own, using dot plots, histograms and the centre and spread. Bivariate analysis compares two variables to look for a relationship, using a scatter plot for two numerical variables. Count the variables in a question to decide which analysis it needs.

Key terms: Univariate, Bivariate, Scatter plot

Causal vs Correlational Relationships

Focus: A correlation means two variables tend to change together, with a direction and a strength. Causation means a change in one variable directly produces a change in the other. Correlation does not prove causation, because a hidden confounding variable can drive both. A controlled experiment is the strongest way to establish a real cause.

Key terms: Correlation, Causation, Confounding variable

Synthesis: Building a Scientific Argument

Focus: A scientific argument has a clear shape: claim, evidence, then reasoning that links the evidence to the claim. A strong argument also names its limitations and considers alternative explanations. Match the strength of your conclusion to the strength of the evidence, and do not overreach.

Key terms: Claim, Evidence, Reasoning

Multiple Choice (10 questions)

1. Which of these is an example of secondary data?

ATiming how long ice cubes take to melt in your own classroom

BDownloading recorded city temperatures from the Bureau of Meteorology

CMeasuring the height of each student in your own class

DCounting the cars that pass your school yourself

2. Why must you clean a dataset before analysing it?

ATo make the spreadsheet look more colourful

BTo delete any values you do not like

CTo make the dataset smaller and faster to open

DBecause errors such as a temperature typed as 310 instead of 31 can ruin the result

3. Calculate the mean of this dataset: 4, 6, 7, 9, 14.

D10

4. Find the median of this dataset: 3, 5, 8, 8, 12, 14.

B12

D11

5. Why is the median often more reliable than the mean when a dataset contains an outlier?

AThe median is always larger than the mean

BThe median only depends on the middle position, so a single extreme value barely moves it

CThe median uses every value, so it is more accurate

DThe median ignores all the data except the largest value

6. Which of these questions is univariate?

AWhat is the typical shoe size in Year 9?

BDo taller students have bigger hand spans?

CDoes temperature affect ice-cream sales?

DDoes more study time relate to higher test scores?

7. A scatter plot of two numerical variables shows points that rise from the lower left to the upper right. This is best described as:

AA negative relationship

BNo relationship

CA univariate distribution

DA positive relationship

8. Ice-cream sales and drownings both rise in summer, but ice cream does not cause drownings. The hidden factor (hot weather) that drives both is called a:

ADependent variable

BPositive correlation

CConfounding variable

DMedian

9. Which is the strongest way for scientists to establish that one variable causes a change in another?

AFinding that the two variables are correlated on a scatter plot

BA controlled experiment that changes only one variable and keeps the others the same

CCollecting more testimonials from customers

DChoosing the headline that sounds most dramatic

10. In a scientific argument, what is the role of the reasoning?

AIt explains how the evidence supports the claim

BIt states the data collected in the investigation

CIt is the statement you are trying to support

DIt counts how many people agree with the claim

Short Answer (3 questions)

SA1

For the dataset 2, 4, 4, 6, 9, calculate the mean, the median, the mode and the range. Show your working. (4 marks)

Write your answer in your book.

SA2

Explain the difference between univariate and bivariate analysis, giving one example question for each. (4 marks)

Write your answer in your book.

SA3

Using the example of firefighters and fire damage, explain why a correlation does not prove causation. Name the confounding variable and describe how a scientist could test for a real cause. (5 marks)

Write your answer in your book.

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Test Your Knowledge

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