Barbeque Forecasting

This chart is a very common design when you want to compare two related data series, which are in quite different units. Here we are testing the hypothesis that people are more likely to have barbeques when the weather is hot! The two series are the daily sales of hamburger buns from a local bakery, and the maximum daily temperature recorded in a nearby village.

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What you might actually notice is something quite interesting – there is a lag of nearly a week between the temperature curve and the bun sales. When the weather gets hot, people decide to have a barbecue, and invite their friends around next week!