Multiple line graph

Command:

Graphs Multiple line graph

Description

Creates a graph that shows consecutive observations of different variables.

Required input

Select the variables of interest, and optionally a filter to include only particular cases in the graph.

Also you can enter a variable containing labels for the X-axis (e.g. dates).

Options

• Logarithmic transformation: if the data require a logarithmic transformation (e.g. when the data are positively skewed), select the Logarithmic transformation option.
• Complete cases only: a case (spreadsheet row) will only be included in the graph when data are available for all variables.
• Markers: mark observations in the graph.
• Trend line: option to plot one of the following trend lines:
  • Moving average trend line: option to plot a moving average trend line for each variable.
    A moving average trendline smooths out fluctuations in data to show a pattern or trend more clearly. A moving average trendline uses a specific number of data points (set by the window width option), averages them, and uses the average value as a point in the trendline. If window width is set to 3, for example, then the average of the first 3 data points is used as the first point in the moving average trendline. The average of the 2nd, 3^rd and 4^th data points is used as the second point in the trendline, and so on.
  • LOESS smoothing: option to plot a LOESS (Local Regression Smoothing) trendline. The degree of smoothing is controlled by the span (%) which is the proportion (expressed as a percentage) of the total number of points that contribute to each local fitted value. Larger values result in smoother trendlines.
  • Isotonic regression curve:
    • in case the tendency of the data is increasing: a fitted free-form line that is non-decreasing everywhere, and lies as close to the observations as possible
    • in case the tendency of the data is decreasing: a fitted free-form line that is non-increasing everywhere, and lies as close to the observations as possible
    The isotonic regression curve is estimated using the pool adjacent violators algorithm.

Example

See also

• Multiple comparison graphs
• Clustered multiple comparison graphs
• Multiple variables graphs
• Clustered multiple variables graphs
• Format graph
• Graph legend
• Add graphical objects
• Reference lines

External links

• Local regression (LOESS smoothing) on Wikipedia.
• Isotonic regression on Wikipedia.
• Moving average on Wikipedia.