Time Series Trend

Description:

• A continous long-term movement over time in the values recorded
  • Upward, downward vs horizontal

Methods to find a trend:

• Inspection:
  • The trend line can be drawn by eye on a graph in such a way that it appears to lie evenly between the recorded points, that is, a line of best fit drawn by eye.
• Regression Analysis:
  • This method makes the assumption that the trend line is a straight line.
  • Periods of time are numbered, and the regression line of the data on those periods is found.
  • That line is taken to be the trend.
• Moving Average:
  • This method attempts to remove seasonal variations by a process of averaging.