Stats GCSE Time Series

What is a time series graph?

A line graph with time plotted on the x axis

What does a trend line do?

Shows the general trend of the data

What kinds of trends are there?

Rising, level or falling

What’s a seasonal variation?

Variations in a time series following a regular time period like days of the week or seasons

Whats a moving average?

An average worked out for a given number of successive observations

What do moving averages do?

Smooth out the fluctuations the data and make the trend line more accurate

How to calculate seasonal variation

Actual value- trend value

How do you plot a moving average?

Plot them at the midpoint of the time interval

How to calculate estimated mean seasonal variation

Mean of all seasonal variation for that season

What’s another way to say seasonal variation

Seasonal effect

What’s another way to say estimated mean seasonal variation?

Average seasonal effect

How to calculate predicted value

Trend line value+ EMSV

What does the reliability of a prediction depend on?

How far into the future the prediction is

How consistent the SV is