chapter 5 Flashcards
what is a time series graph?
a line graph with time plotted on the horizontal axis
what is a general trend?
the way that data changes over time
what does the trend line show?
the general trend of the data
what might a trend line show?
a tendency to rise, fall or stay level
variations in a time series may be…
a general trend
seasonal variations
what is seasonal variation?
variation in a time series following a regular time period, like the days of a week or seasons in a year
what is a moving average?
an average worked out for a given number of successive observations
moving averages on time series graphs show what?
the trend
what is the formula for seasonal variation?
actual value- trend value
what can you use to predict the sale figures at some future time?
a trend line and the estimated mean seasonal variations
what is the formula for predicted value?
trend line value + estimated mean seasonal variation
what can mean seasonal variation also be called?
average seasonal effect
what does the reliability of any prediction depend on?
how far into the future the prediction is made
how good the estimates of the mean seasonal variations are at predicting future seasonal variations
