Collecting and Organising Data

In a Nutshell

Data can be collected using tally charts and organised into frequency tables so patterns are easier to spot.

Before you can draw a chart or calculate an average, you need to collect and organise your data.

A tally chart is a quick way to record data as you collect it. Each item is marked with a short vertical line. Every fifth tally is drawn diagonally across the previous four to make a gate (group of five), which makes counting easier.

The frequency is the total count for each category. A frequency table has columns for Category, Tally and Frequency.

Data can be categorical (words, like favourite colour) or numerical (numbers, like shoe size). Knowing the type helps you choose the right chart later.

Tally chart builder A table with columns for Category, Tally and Frequency. Click on a category row to add tally marks. Every fifth tally draws a gate (diagonal strike-through line). Category Tally Frequency

Watch it work

Question: 20 pupils were asked their favourite colour. The results were: Red, Blue, Green, Blue, Red, Red, Yellow, Blue, Green, Red, Blue, Blue, Yellow, Red, Green, Blue, Red, Blue, Green, Red. Organise this in a frequency table.

Have a go

Q1. What does a single gate in a tally chart represent?

Q2. A tally for "Bus" shows 3 gates and 2 extra lines. What is the frequency?

Q3. Is "shoe size" categorical or numerical data?

Q4. Freya's frequency table has totals 8, 12, 5 and 3 for four categories. She surveyed 30 people. Has she made an error?