Data Handling - Interpreting Data

Tally Marks are a quick way to record data using vertical lines. For every five items, we draw four vertical lines and one diagonal line crossing through them ($||||$ with a slash), forming a 'bundle' that makes it easy to count by $5s$.

A Frequency Table is a chart used to organize data. It usually has three columns: the Category name, the Tally marks, and the Frequency (the total number written as a digit, like $8$ or $12$).

A Pictograph uses pictures or symbols to represent data. A very important part of a pictograph is the Key (or Legend), which tells you what each picture stands for. For example, a single star symbol might represent $2$ students ($1 \text{ star} = 2 \text{ students}$).

Bar Graphs represent data using rectangular bars. The height or length of the bar shows the value. The graph has two axes: the horizontal x-axis (usually for categories) and the vertical y-axis (usually for the scale/numbers).

The Scale on a bar graph is the set of numbers along the y-axis that helps us measure the bars. Scales don't always count by $1s$; they can count by $2s, 5s, 10s,$ or more ($0, 10, 20, 30...$). We must check the scale to read the value of a bar correctly.

Interpreting Data means lookings at a graph to answer questions. We identify the 'Most Popular' (the tallest bar or most symbols) and the 'Least Popular' (the shortest bar or fewest symbols) to understand the results of a survey.

Comparing Data involves finding the difference between two categories. To find how many more items are in Category A than Category B, we use subtraction ($Value A - Value B$).

The Total represents the sum of all data collected. To find the total number of people surveyed, we add the frequencies of every category together ($Sum = F_1 + F_2 + F_3...$).