Data Handling - Pictographs

Definition of a Pictograph: A pictograph is a visual way of representing data using pictures or symbols. It is a table where one column lists the categories and the other column displays a series of identical icons to represent the quantity for each category.

The Importance of the Key: The key is a crucial instruction, usually found at the bottom or corner of the graph, that defines the numerical value of one single symbol. For example, a key might state: $1 \text{ symbol} = 10 \text{ units}$. Without the key, the pictograph cannot be interpreted correctly.

Using Half-Symbols: When a data value is exactly half of the value assigned to one full symbol, a half-picture is used. Visually, this looks like the icon has been cut vertically down the middle. If $1 \text{ circle} = 8 \text{ items}$, then a half-circle represents $\frac{8}{2} = 4$ items.

Organizing Data in Rows and Columns: Pictographs are structured like a grid. The left-most column identifies the items being counted (like days of the week or names of fruits), and the right-hand area contains horizontal rows of icons aligned next to each item for easy comparison of lengths.

Scaling Data: Pictographs help simplify large numbers. Instead of drawing $100$ individual dots, we can use a scale where $1 \text{ icon} = 20 \text{ units}$, meaning we only need to draw $5$ icons ($100 \div 20 = 5$).

Comparing Quantities Visually: By looking at the length of the rows of symbols, you can quickly identify which category has the 'most' or 'least' without even doing math. The longest row of icons represents the highest frequency, and the shortest row represents the lowest frequency.

Calculating Totals: To find the actual total for any category, you count the number of full symbols, multiply by the key value, and then add the value of any partial/half-symbols.