Numbers and graphs are everywhere, but in Thinking Skills (9694), we don't just look at them—we try to understand the "story" they are telling. This chapter focuses on explaining trends. It’s not enough to say, "The line goes up"; we want to know why it goes up and what factors are pushing it in that direction.

Whether you are preparing for Paper 1 (Problem Solving) or Paper 3 (Problem Analysis and Solution), being able to look at a messy set of data and find the underlying reason for a change is a vital skill. Don't worry if you find charts intimidating at first; we will break them down step-by-step!


1. What is a Trend?

A trend is the general direction in which something is developing or changing over time. Think of it as the "big picture" movement, ignoring the small day-to-day wobbles.

Common types of trends include:

  • Upward Trend: Data points generally increase (e.g., \(+5\%\) growth each year).
  • Downward Trend: Data points generally decrease.
  • Stable Trend: Data stays roughly the same over a period.
  • Fluctuating/Cyclic Trend: Data goes up and down in a predictable pattern (like seasonal sales of umbrellas).

Quick Tip: If you are asked to identify a trend, you describe what is happening. If you are asked to explain a trend, you must suggest a reason why it is happening based on the information provided in the scenario.


2. The Difference Between Describing and Explaining

This is a common trap for students! Let’s look at the difference:

Describing: "The number of people visiting the park increased from \(100\) in January to \(500\) in July." (This just states the facts.)

Explaining: "The increase in park visitors between January and July can be explained by the warmer weather and longer daylight hours during the summer months." (This provides a reason for the change.)

In your exam, the command word "Explain" requires you to make the relationships between things clear and support your answer with relevant evidence from the data provided.


3. Step-by-Step: How to Explain a Trend

When you are faced with a table or a graph and asked to explain a trend, follow these steps:

Step 1: Look for the Overall Pattern

Is the data generally moving in one direction? For example, if you see that a company's profits are rising by roughly \(10\%\) every year, you have identified a steady upward trend.

Step 2: Identify "Anomalies" (The Blips)

An anomaly is a piece of data that doesn't fit the overall trend. For example, if profits rose every year for five years but crashed in Year 3, Year 3 is the anomaly. To explain the trend fully, you often have to explain why that one year was different.

Step 3: Search for External Factors

The exam scenario will usually give you clues. Look for changes in:
• Rules or Laws: Did a new tax start?
• Capacity: Did a shop open more checkouts?
• Time/Season: Is it a holiday period or a weekend?
• Price Changes: Did the cost of the item go up?

Step 4: Link Cause and Effect

Use logical reasoning to connect the data to the factor. Example: "The sudden drop in bus passengers in \(2024\) is likely explained by the \(25\%\) increase in ticket prices introduced in January of that year."


In Thinking Skills problems, trends are rarely accidental. They are usually caused by specific mechanics within the model or scenario. Here are things to look out for:

Seasonality

Does the data repeat a pattern every \(7\) days (weekly cycle) or every \(12\) months (annual cycle)? Example: Gym memberships usually spike in January because of New Year's resolutions. This explains a recurring annual trend.

Lagging Effects

Sometimes a change happens, but the trend doesn't shift immediately. Example: If a town bans plastic bags in June, the trend of decreasing plastic waste might not show up clearly until August as people use up their old supplies.

Thresholds and Saturation

Sometimes a trend stops because it hits a limit. If a theater has \(200\) seats, the trend of increasing ticket sales must stop at \(200\). The trend levels off because the capacity has been reached.


5. Common Mistakes to Avoid

1. Over-explaining: Don't bring in outside knowledge that isn't in the text. If the data is about a fictional planet, don't try to explain it using Earth's economics! Stick to the provided evidence.

2. Confusing Correlation with Causation: Just because two things happen at the same time doesn't mean one caused the other. Ensure there is a logical relationship between the factor and the trend. (See the chapter on "Identify logical relationships" for more on this).

3. Ignoring the Scale: Always look at the numbers on the axes of a graph. A trend might look "huge" visually, but if the scale only goes from \(99\) to \(100\), the actual change is very small.


Summary: Key Takeaways

• Identify first: Spot the general direction (up, down, or cyclic).

• Look for the "Why": Use the scenario's details (price changes, time of year, capacity limits) to find a reason for the movement.

• Address anomalies: If the trend breaks, look for a specific event in the scenario that explains that "blip".

• Be precise: Use the command word "Explain" to show how the data relates to the real-world situation described in the problem.


Note: For more information on how to handle the data itself before explaining it, see the chapter on "Transform data". To see how these trends fit into larger systems, check out "Apply a complex model".