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D1.2 · Collect, organize, and store secondary one-variable data

Learn to collect, organize, and store secondary one-variable data through clear examples and targeted practice.

Ontario Grade 11 Mathematics

Data Management

Ontario Grade 11 MBF3C — Study-guide label D1.2

Data are recorded information. In this lesson, you will work with one variable: one feature measured or counted for each person, place, or item. Secondary data are information collected earlier by someone else, rather than gathered firsthand for your current task. You will learn how to find suitable secondary data, organize the values, and store them with enough context to use them responsibly.

What you will learn

Explain what secondary one-variable data are.
Plan and carry out a careful search for data that already exist.
Organize, label, and store the data so they can be checked and used.

1. Bridge: one variable and two sources

A variable is a feature that can have different values. For example, if you record the number of library visits made by each student in one month, the variable is “library visits per student.” Each recorded number is a data value.

A data set is a group of recorded values. A one-variable data set has one main feature recorded for each case. A case is the person, place, or item represented by one entry. In the library example, each student is a case and the number of visits is the variable.

Primary data are collected directly for the question at hand, such as by asking students to report their visits. Secondary data already exist because another person or organization collected them for another purpose or time. A school board report listing library visits by school is a possible secondary source.

This lesson is about collecting secondary data in the sense of locating and obtaining existing records, then organizing and storing them. It is not about making new observations or deciding what a set of values shows.

One variable means one feature is recorded for each case.
Secondary data already exist before your current investigation.
A source is where the data can be found.

2. Find and assess a useful source

Begin by writing a focused question and naming the variable you need. For example: “What was the monthly rainfall, in millimetres, in each month of a particular year at one weather station?” The variable is monthly rainfall; a case is one month.

Search for a source that fits the question. It might be a public report, a data file, or an organization’s published record. Before using it, check who collected the values, what the values represent, and when and where they were collected. A source that reports daily rainfall cannot directly answer a question about monthly totals unless the monthly totals are also provided.

Check the units and definitions. A value of 12 could mean 12 millimetres of rain, 12 centimetres of snow, or something else. The label and source notes tell you what it means. Also check that the cases are consistent: for example, every value should refer to the same kind of time period and location if your question requires that.

Record source details while collecting the values. Note the organization or author, the report or file name, the date or period covered, the location, the variable definition, and the units. Include a page, table, or file location when available. These details make it possible to identify and check the original information later.

Match the source to the question and variable.
Check definitions, units, time period, and location.
Keep source details with the values.

3. Organize and store the values

Once you have obtained the values, give the data set a clear title. Use a simple table with one row for each case and a heading for the variable. Include units in the heading when appropriate. If the case itself is important, include a case label in a separate column.

Keep the original values unchanged when transferring them. Check the copy against the source, especially decimal points, signs, and units. If you make a correction or change the format, note what you changed. Do not silently mix values measured in different units; record the unit conversion clearly if a common unit is needed.

Store the organized data in a suitable place, such as a clearly named digital file or a labelled paper record. A useful file name identifies the topic and period. Keep the source details in the file or with it, so they do not become separated from the values. Follow any access or privacy limits stated by the source.

A compact record can show how the pieces fit together. The example below is a template; its entries are invented to show the layout, not actual weather records.

Use clear titles and column headings.
Preserve values and document any changes.
Store source details with the data set.

Illustrative layout for a secondary one-variable data set

Case: month	Monthly rainfall (mm)
January	Value copied from source
February	Value copied from source
March	Value copied from source

Worked example

Example 1: Monthly rainfall from a report

A student needs monthly rainfall totals for one town for a school project. A weather organization has published a table for the town and year. Describe how the student should collect, organize, and store this secondary one-variable data.

Define the data needed
The question calls for one value for each month. The variable is monthly rainfall, and the cases are the months. The unit should be copied from the report rather than guessed.
Check the source
Confirm that the report is for the correct town and year and that it gives monthly totals, not daily measurements. Check the rainfall unit and any notes explaining how the totals were recorded.
Organize the entries
Copy the twelve reported values into a table with one row for each month. Use a heading that names the variable and its unit. Compare each copied value with the source to reduce transcription errors.
Store the record
Save the table with a descriptive title. Include the organization, report name, town, year, access date, and table location. Keeping these details with the values lets another person find the same source.

Answer: A titled table with one row per month and a clearly labelled rainfall column, stored together with the report details.

Check: The cases are all months in the selected town and year, and each value represents monthly rainfall in the source’s stated unit.

Worked example

Example 2: Comparing published school counts

A school board file lists the number of students enrolled at six schools for a named school year. A learner wants a one-variable data set of enrolment counts. What should the learner check and record before storing it?

Identify the variable and cases
The variable is the number of students enrolled. Each school is one case, so the file supplies six values if all six schools are included.
Check what the counts mean
Read the file notes to confirm that all values refer to the same school year and use the same enrolment definition. Check whether the counts include the same student groups at every school.
Make a consistent table
Use one row for each school and a column labelled “Enrolment (students).” Copy the six counts as shown. Keep school names as case labels so each count remains attached to the right school.
Keep source information
Store the table with the board’s name, file title, school year, date accessed, and any relevant notes about the count definition. This preserves the context needed to interpret the numbers.

Answer: A six-row table with school labels and enrolment counts, plus the school year, definition, and source details.

Check: Every row represents one of the six schools, and all counts use the same stated year and definition.

Common mistakes and how to avoid them

Using a source that has the right topic but the wrong measure, such as daily values when monthly totals are needed.

Correction: Check that the values match the variable and time period in the question.

Copying numbers without their units or definitions.

Correction: Record the units and relevant source notes with the data.

Leaving out where the values came from.

Correction: Keep the organization, file or report name, period, and location with the stored data.

Changing a value while transferring it without noting the change.

Correction: Check the copy against the source and document any formatting or conversion changes.

Lesson summary

Secondary data already exist and were collected by someone else.
Define the variable and cases before searching.
Check the source, definitions, units, period, and location.
Organize values with clear labels and preserve the original information.
Store source details with the data so the record can be checked later.

Check your understanding

Question 1

A published report gives the daily temperatures for a city. Which choice best matches a request for monthly average temperatures?

Use the daily values as if each one were a monthly average.
Check whether the report or another suitable source provides monthly averages for the required city and period.
Copy the values and label them monthly averages.
Use the report without checking its units or dates.

Show answer and explanation

Check whether the report or another suitable source provides monthly averages for the required city and period.

The data must match the requested variable and time period. Daily temperatures are not monthly averages, so the learner should find a suitable source or report that provides the requested measure.

Question 2

A data file lists the number of books borrowed by each branch in a library system. What is one case?

The number of books borrowed
A library branch
The file’s access date
The unit used for a different measure

Show answer and explanation

A library branch

Each branch is one case, and the number of books borrowed is the variable recorded for that case.

Question 3

Which record is most useful to keep with a stored secondary data set?

Only the copied values
The values and a note identifying the source, period, and units
A new title that does not describe the values
Values from several sources mixed without labels

Show answer and explanation

The values and a note identifying the source, period, and units

Source, period, and unit details give the values context and make the data set easier to identify and check.

Key terms

Variable: A feature that can have different values and is recorded for each case.
Case: The person, place, or item represented by one entry in a data set.
Data set: A group of recorded data values.
Primary data: Data collected directly for the current question or investigation.
Secondary data: Data that already exist because someone else collected them earlier.
Unit: The measurement label that explains what a numerical value counts or measures, such as millimetres or students.

Continue through MBF3C

View the complete MBF3C Ontario Grade 11 Mathematics curriculum and lessons

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About this lesson and its review

Published by DoAssignment. This reviewed lesson follows Ontario Grade 11 Mathematics (MBF3C), expectation D1.2. It is a study resource, not an official curriculum publication.

Before publication, content is checked for structure, mathematical or chemical notation, calculations, course boundaries, and readability. Errors can still occur, so corrections are welcomed.

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