Normal curve tail area

0. Quick guide - background

In this module:

  1. Construct a chart of the normal distribution density function - using area charts (Fig 1.)
  2. Compare the tail area color for fine and coarse step sizes (Fig 1.)
  3. Perform a visual comparison to the Peltier (2013) version with its XY-area chart combination plus date axis (Fig 1.)

1. Normal tail area

Circle numbers refer to image components in figure 1.

xlf alertxlf :: combo area - area :: step 0.1

The coarse step increment causes the left margin of the blue tail area to slope (1.5 at the base to 1.6 at the peak).

xlf alertxlf :: combo area - area :: step 0.01

The finer step increment (0.01) returns a left margin of the blue tail area that visually appears to be vertical.

xlf alertPeltier :: combo area - XY with smoothed lines :: step [modified date]

Peltier (2013) uses includes an XY type chart with secondary axis and X values treated as dates.

See Peltier (2013) for details.

95 tail area
Fig 1: - step 0.1; step 0.01; Peltier step date 1 to 10000

2. Discussion

An examination of figure 1, items 2 and 3 suggests that the area plot with fine increments is equivalent to the Peltier XY plot, at least for a tail area.