Data quality: reliability

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which data is more reliable?

A Student attendance figures from the school's official records

B Attendance figures a student guessed from memory

2. True or false: Reliable data gives consistent results when it is collected again in the same way.

A False

B True

3. A class measures the temperature of the same room at the same time using the same thermometer three days in a row. The readings are 22°C, 22°C and 23°C. What does this suggest?

A The data is reliable because the results are consistent

B The data is unreliable because the readings are not all identical

4. Which source is more credible for data about Australian population numbers?

A An anonymous social media post

B The Australian Bureau of Statistics

5. Which survey is likely to give more reliable results?

A A survey of 500 randomly chosen students

B A survey of 5 friends

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1reliability		AData is reliable when it comes from a trustworthy source and gives consistent results if collected again in the same way
2sample_size = 1000		BAn anonymous blog is not a credible source, so the data should not be called reliable without checking it against a trusted source.
3A source is credible, so data from it is more reliable		CA sample of only 3 is too small to be very reliable because results could change a lot if it were collected again.
4Repeating the same collection method should give consistent results, which shows reliability		DA larger sample gives more reliable results than a very small sample because one-off or odd answers have less effect
5source = "anonymous blog post" # reliable		Esurvey1 = 72 and survey2 = 71
6sample_size = 3 # very reliable		Fsource = "Australian Bureau of Statistics"

Definitions

reliability

Fill in the Blanks

Complete each line of code by filling in the missing parts.

Data is ________ if results are consistent

Reliable data comes from a ___________ source

Collect it again and get __________ results

A larger ______ size makes data more reliable

Repeatable: use the same ______ each time

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A source ← "ABS census"

B trusted ← TRUE

C size ← 500

D IF trusted OR size > 100

E OUTPUT "Reliable"

Question 2

A result1 ← 72

B result2 ← 71

C diff ← result1 + result2

D IF diff <= 2 THEN

E OUTPUT "Consistent"

Question 3

A readings ← [48, 51, 50, 49]

B total ← SUM(readings)

C count ← LENGTH(readings)

D average ← total * count

E OUTPUT average

Question 4

A sample_size ← 20

B IF sample_size > 30 THEN

C OUTPUT "Collect more data"

D ENDIF

Question 5

A source ← "random blog"

B credible ← FALSE

C IF credible = TRUE THEN

D OUTPUT "Check source"

E ENDIF

Answer Key

Data quality: reliability

Section A: Quick Questions

A — Student attendance figures from the school's official records

B — True

A — The data is reliable because the results are consistent

B — The Australian Bureau of Statistics

A — A survey of 500 randomly chosen students

Section B: Match the Pairs

reliability → Data is reliable when it comes from a trustworthy source and gives consistent results if collected again in the same way

sample_size = 1000 → A larger sample gives more reliable results than a very small sample because one-off or odd answers have less effect

A source is credible, so data from it is more reliable → source = "Australian Bureau of Statistics"

Repeating the same collection method should give consistent results, which shows reliability → survey1 = 72 and survey2 = 71

source = "anonymous blog post" # reliable → An anonymous blog is not a credible source, so the data should not be called reliable without checking it against a trusted source.

sample_size = 3 # very reliable → A sample of only 3 is too small to be very reliable because results could change a lot if it were collected again.

Section C: Definitions

reliability — Data is reliable when it comes from a trustworthy source and gives consistent results if collected again in the same way. A larger sample size also makes results more reliable.

Section D: Fill in the Blanks

Data is reliable if results are consistent

Reliable data comes from a trustworthy source

Collect it again and get consistent results

A larger sample size makes data more reliable

Repeatable: use the same method each time

Section E: Spot the Error

D — Reliable data needs a trustworthy source AND a large enough sample. OR would pass data with only one of these. It should be IF trusted AND size > 100.

C — To check whether repeated collection gives consistent results, you find the difference between the two results, not the sum. It should be diff ← ABS(result1 - result2).

D — The average of repeated readings is the total divided by the number of readings, not multiplied. It should be average ← total / count.

B — A small sample is less reliable, so the warning should show when the sample size is LESS than 30. It should be IF sample_size < 30 THEN.

C — The warning to check the source should appear when the source is NOT credible. It should be IF credible = FALSE THEN.