Reviewed by Oct 05, 2020| Updated on
A hockey stick chart refers to a line chart in which a sharp increase occurs suddenly after a short period of inactiveness. The line joining the data points looks like a hockey stick. These charts have been used in the world of business. They are visual representations to show dramatic shifts, such as global temperatures and poverty statistics.
A hockey stick consists of a tip, a slight curve, and a long length. A hockey stick chart displays low-level (y-axis) data activity over a short period (x-axis), then a sudden bend indicative of an inflexion point, and finally a steep, long, and straight elevation.
The chart of the hockey stick may command immediate attention. A sudden and dramatic shift from a flat-period to what is visible in a hockey stick chart in the direction of data points is a clear indicator that more focus on causative factors should be given. Where the data change occurs over a short period, it is essential to assess if the change is an aberration or a fundamental change.
If the blade points up the tip of the hockey stick, a sharp rise precedes the stable time. In comparison, if it points down, a steep decline follows a stable period.
The Times of India publication reported that the rise of COVID-19 cases in India as early as April 2020 was taking hockey stick shape. It was quoted that "In a pandemic, the numbers will keep increasing for a while, and the hockey stick will become longer."
The chart is generally used in research laboratories, such as medicine or environmental studies. For example, scientists have plotted data about global warming on a chart that follows a pattern of hockey sticks. The map is also common to social scientists. This process has delineated several assumptions about the rate of increase in poverty.
A hockey stick map is useful when making a presentation in which you want to take drastic action. It is successful because everyone can see what has happened or is going to happen. People prefer to use this kind of chart to display a slowly rising duration, and a rapid upswing followed. If the sudden upward or downward change takes place over a brief period, then it is important to decide why.
The word 'hockey stick' for charts was invented in 1999 by Jerry Mahlman, an American meteorologist and climatologist. He used that term to describe the global climate pattern of Mann, Bradley, and Hughes. Up until 1900, the graph showed a relatively flat downward movement, and then a sharp rise confirming global warming.