Chapter 5: Time Series Flashcards
What is a time series graph?
A line graph with time plotted on the x-axis
Used to spot trends that may be going up, down, or fluctuating.
What does a trend line show?
The general trend of the data
It ignores fluctuations and follows the general pattern of the data.
What are the types of trends that a trend line can indicate?
- Rising (upwards) trend
- Falling (downwards) trend
- Level trend
What are moving averages?
An average worked out for a given number of successive observations
They help to smooth out fluctuations in data.
How are moving averages plotted?
At the midpoint of the time interval
Do not join the up; use Line of Best Fit (LOBF).
Fill in the blank: The formula for a 3 point moving average is _______.
(Value1 + Value2 + Value3) / 3
What are seasonal variations in a time series?
A pattern that repeats at a specific point every cycle
They follow a regular time period, like days of the week or seasons.
What is the formula for calculating seasonal variation at a point?
Seasonal Variation = Actual Value - Trend Value
What does EMSV stand for?
Estimated Mean Seasonal Variation
Also called Average Seasonal Effect.
How is the Estimated Mean Seasonal Variation calculated?
Mean of all the seasonal variations for that season
What can be used to predict future values in a time series?
The trend line and estimated mean seasonal variations
Fill in the blank: The predicted value is calculated as _______.
Trend Line Value + EMSV
