Data Collection Examples in Statistics
Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Data Collection.
This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Statistics.
Concept Recap
The systematic process of gathering information to answer questions, using methods like surveys, experiments, or observations.
Imagine you want to know your class's favorite ice cream flavor. You can't just guess - you need to actually ask everyone and write down their answers. That's data collection! It's like being a detective who gathers clues before solving a mystery.
Read the full concept explanation →How to Use These Examples
- Read the first worked example with the solution open so the structure is clear.
- Try the practice problems before revealing each solution.
- Use the related concepts and background knowledge badges if you feel stuck.
What to Focus On
Core idea: Data Collection starts by naming the question and variable before any graph or summary is chosen.
Common stuck point: Students often know a procedure related to data collection but skip the recognition step: Have I named the variable, the possible responses, and the reason the responses may vary? That leads to a calculation or graph that looks reasonable but answers a different question.
Sense of Study hint: Ask: Have I named the variable, the possible responses, and the reason the responses may vary?
Common Mistakes to Watch For
Before you work through the examples, skim the mistake guide so you know which shortcuts and sign errors to avoid.
Worked Examples
Example 1
easyTo find the favorite school subject of all students, a researcher asks every student in just one class. Is this a good way to collect the data?
Answer
First step
1
The question is about ALL students, not one class.
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Example 2
mediumA student wants to know the average height of all th graders in her school. She measures only her closest friends. What's the problem with her data?
Example 3
mediumA student wants to count birds in a tree but can only see one branch. She counts birds on it and concludes there are birds in the whole tree. Is her data complete?
Example 4
mediumA survey asks: 'Don't you agree pizza is the best lunch?' Is this a good survey question?
Example 5
hardA scientist measures plant heights (): . What is the median of this data set?
Example 6
hardA student records the heights of her classmates. She makes a careless mistake and records one height as cm instead of the true cm. The first reported mean was cm. What is the corrected mean?
Example 7
hardA student observes a parking lot once per day for days and counts cars. What is the mean number of cars per day?
Example 8
challengeA small school has students. To estimate the average backpack weight, the principal wants a sample size of (). He asks every th student in line at the cafeteria. What kind of sampling is this, and is it acceptable?
Example 9
easyA student wants to find out the favourite sport of students in her school. She decides to ask every student in her class. Is this a good method of data collection? Explain.
Example 10
easyClassify each data-collection method as a survey, an observation, or an experiment: (a) Recording how many cars pass a junction each hour. (b) Asking 50 people their favourite colour. (c) Giving one group of plants fertiliser and another group none, then measuring growth.
Practice Problems
Try these problems on your own first, then open the solution to compare your method.
Example 1
easyA survey records favorite fruit from 6 students: apple, apple, banana, apple, banana, kiwi. How many chose apple?
Example 2
easyTo learn the class's favorite sport, a student asks all 25 classmates. How many people were surveyed?
Example 3
easyA weather log records rain on 4 of 7 days. On how many days did it NOT rain?
Example 4
easyA student measures the height of 5 plants. Each measurement is one data point. How many data points were collected?
Example 5
easyA poll asks 10 people yes or no. 6 say yes. How many say no?
Example 6
easyA teacher collects shoe sizes from 8 students. How many individuals contributed data?
Example 7
easyA survey of pets gives: dog, cat, dog, fish, dog. How many distinct categories of pet appear?
Example 8
easyA student asks 12 people their favorite color and records every answer. If 3 answers were lost, how many were successfully recorded?
Example 9
mediumA survey records lunch choice for 30 students. 14 chose pizza, 9 chose salad, the rest chose soup. How many chose soup?
Example 10
mediumIn a 5-day temperature log the readings are 20, 22, 19, 21, 18 degrees. What is the range (max minus min) of the collected data?
Example 11
mediumA class of 40 is surveyed about transport. Half walk, a quarter bike, the rest take the bus. How many take the bus?
Example 12
mediumTwo students each survey 15 people, but 5 people were asked by both. How many distinct people were surveyed in total?
Example 13
mediumA survey planned 50 responses but achieved an 80 percent response rate. How many responses were collected?
Example 14
mediumA pet survey records: dog 7, cat 5, bird 3, fish 5. How many pets were recorded in total?
Example 15
mediumA student observes cars for 1 hour and counts 18 red, 12 blue, and some white, recording 45 cars total. How many white cars were counted?
Example 16
mediumA survey gathers ages 10, 12, 11, 13, 14 from 5 students. What is the total of all collected ages?
Example 17
challengeA survey of 100 students reports 60 like math and 50 like science, with 25 liking both. How many like neither subject?
Example 18
challengeA study collects data on 3 days. Day 1 had 12 responses, each later day had 4 more than the day before. How many responses were collected over all 3 days?
Example 19
challengeA survey must reach a margin of error needing at least 4 times its pilot sample of 35 people. What is the minimum total sample required?
Example 20
mediumA survey of 24 students records handedness: 18 right-handed, the rest left-handed. How many are left-handed?
Example 21
easyA teacher asks students their favorite season. say summer, say winter, say spring, the rest say fall. How many say fall?
Example 22
easyA survey asks kids whether they have a sibling. say yes. How many say no?
Example 23
easyA class survey records favorite pets: dog 12, cat 8, fish 3, bird 2. How many students were surveyed?
Example 24
easyA tally chart shows: red |||| ||, blue |||, green ||||. How many people chose blue?
Example 25
mediumA class of is surveyed about lunch. Half choose pizza, a quarter choose pasta, the rest choose salad. How many choose salad?
Example 26
mediumA week-long log shows daily steps: . How many days had more than steps?
Example 27
mediumA student surveys classmates about a new lunch menu. like it, dislike it, are unsure. What fraction like the new menu?
Example 28
mediumIn a -day temperature log, the high temperatures (°F) are . What is the range of the data?
Example 29
mediumA student counts cars passing a corner: red, blue, white, and other. What percent are red?
Example 30
hardA teacher wants the average reading speed of all students in the school but doesn't have time to test everyone. She tests randomly chosen students. What is this kind of data collection called?
Example 31
hardA class of takes a quiz. The mean score is . What is the total score of all students combined?
Example 32
hardTo learn the most popular lunchtime among workers at a large company, you survey ONLY employees who arrive between 11:30 and 12:00. What bias is in this data?
Example 33
easyA town council wants to know whether residents support building a new park. They place a survey form in the local library. Give one reason this method might produce biased results and suggest an improvement.
Example 34
easyA school wants to know how many students ride the bus. They ask the first 20 students who enter through the front door on Monday morning. Identify one source of bias and suggest a better method.
Related Concepts
Background Knowledge
These ideas may be useful before you work through the harder examples.
tally chart