M4.7.7 For the adult
Data over time
The rain in a town rises and falls every year. How can I see a slow change over the years, and the ups and downs that repeat?
What this chapter teaches
A time series is plotted in order, with time across. The trend is the general direction. A seasonal pattern is a rise and fall that repeats after a fixed number of readings. Averaging over a whole cycle shows the trend.
Three questions to ask
There is no one right wording. Listen for the idea.
- How would you describe the trend in a graph where the readings zigzag but each year is higher than the last?
- How can you tell that a pattern repeats every 7 days?
- Why should we be careful when using a trend to predict far into the future?
After the chapter, the learner can
- Plot a time series and describe the trend
- Spot ups and downs that repeat in a time series
What they copy into their notebook
Time series: readings in order, time across. Trend: the general direction. Seasonal pattern: a rise and fall that repeats. The mean over a whole cycle shows the trend.