5.4 Graphs: Matching Data to a Graph and Reading Values Quickly

5.4 Graphs: Matching Data to a Graph and Reading Values Quickly

Graphs appear on Wonderlic's list of SLE and SLE-Q item types. One of Wonderlic's published sample questions shows the most distinctive format. It gives a short list of numbers, which were orders over a five-hour period, and asks which graph best represents the trend. Other graph items give you a chart and ask you to read or compare values. Both formats can be answered quickly if you know what to look at first. It is rarely the fine detail.

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Format 1: "Which Graph Matches These Numbers?"

When the numbers are given and the graphs are the answer choices, you do not need to plot anything. Turn the numbers into a shape signature, meaning the sequence of rises and falls and their relative sizes. Then find the graph with that signature.

Practice data (not Wonderlic's item): hourly orders of 30, 95, 70, 120, 205.

Signature: large rise, small dip, medium rise, largest rise. The lowest point is first and the highest point is last.

The Four-Check Elimination Order

1. Endpoints. Is the first value lower or higher than the last? This often eliminates half the choices in one glance.
2. Direction pattern. Count the ups and downs: up, down, up, up. Reject any graph with a different pattern.
3. Extremes. Where are the minimum and the maximum? Here the minimum is point 1 and the maximum is point 5.
4. Relative sizes. Only if two graphs survive, compare step sizes. Here the dip (−25) is smaller than any rise, and the last rise is the steepest.

Graph-matching choices may show bars instead of a line. Apply the same signature to the tops of the bars.

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Format 2: Reading a Graph

When the graph is given and the choices are numbers or statements, read the frame before the data:

1. Title and labels. What is being counted, and in what unit (dollars, patients, percent, thousands)?
2. Axis scale. What does each gridline represent? Does the vertical axis start at zero?
3. The question's target. A single value, a difference, a total, a percentage change, or a trend?

Bar Graphs

Read each bar's top against the scale. For differences, subtract bar heights. For percentage change, use the starting bar as the base (Section 4.3).

Example: A clinic saw 12 patients Monday, 18 Tuesday, 9 Wednesday, and 15 Thursday. How many more patients came on Tuesday than on Wednesday, as a percentage of Wednesday? 18 − 9 = 9, and 9 ÷ 9 = 100% more. A common mistake is to divide by Tuesday's 18 and answer 50%.

Line Graphs

A line graph shows change over time. The steepest segment is the fastest change. A flat segment means no change. A segment sloping down means a decrease, even if the values are still high.

Pie Charts

Slices are parts of a whole that totals 100%. To turn a slice into an amount, multiply the percentage by the total. If rent is 35% of a $2,400 monthly budget, rent is 0.35 × 2,400 = $840. A whole circle is 360°, so each 1% of the pie equals 3.6°, and a 25% slice is a 90° right angle.

Tables

Find the row and column first, then read the cell where they meet. Check the column heading for units, such as "in thousands" or "per hour," before you compute.

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The Truncated-Axis Trap

A vertical axis that starts above zero makes small changes look dramatic. Suppose a line graph's axis starts at 90, and sales rise from 92 to 96. The line may look like it doubles, but the real increase is 4 ÷ 92 ≈ 4.3%. Before judging "how much" from a picture, read the numbers on the axis, not the heights on the screen.

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Estimation Is Usually Enough

Graph items give you visual answers, so exact arithmetic is rarely needed:

• Round the readings to the nearest gridline, then check which answer choice is closest.
• Use benchmarks. A bar about half the height of another is about 50% of it. A slice about a quarter of the circle is about 25%.
• Compute exactly only if two choices are close.

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Common Traps

1. Reversed order. A graph whose shape is the mirror image of the data, with the highest point first instead of last, is a classic wrong choice. Always check the endpoints.
2. Wrong base for percentages. A percent change divides by the starting value, not the ending value.
3. Ignoring units. A vertical axis labeled "thousands of dollars" makes a bar at 4 worth $4,000.
4. Reading the wrong series. When a graph has two lines or paired bars, check the legend before reading values.

Graph items combine the percentage skills from Section 4.3 with careful reading. If you drill the shape-signature method, a graph-matching item usually takes seconds.