Data vizualization

Purpose

There are several representations depending on the type of data under consideration. Six kinds of graphics are available depending on the selected data in the list of Y-Axis and X-Axis.

Spaghetti

The spaghetti plot represents Y w.r.t. X by individual when both X and Y are continuous variable. This is one of the most used graphics. One can see for example a continuous observation with respect to time which is the first graphic of interest. In the warfarin example, one can plot the concentration w.r.t. time as in the following figure

datxplore_Spaghetti

Scatter

The scatter plot represents dots of Y versus X when both X and Y are continuous variable and X is a covariate. In the warfarin example, one can plot the concentration w.r.t. the weight as in the following figure

datxplore_Scatter

Box & Whiskers Plot

The box blox represents the statistical representation of a continuous variable in box plot w.r.t. a discrete variable. It is a convenient way to graphically depict groups of numerical data through their quartiles. Box plots may also have lines extending vertically from the boxes (whiskers) indicating variability outside the upper and lower quartiles. In the warfarin example, one can plot the distribution of the weight w.r.t. the gender as in the following figure

datxplore_Box

It is very relevant to see the variation of an observation or a continuous covariate.

Cumulative histogram

The cumulative histogram represents a cumulative count of a discrete variable w.r.t. a continuous variable. In the warfarin example, one can plot the cumulative count of the gender w.r.t. the weight as in the following figure

datxplore_Cumulative

Histogram by group

The histogram plot represents a cumulative count of a discrete variable w.r.t. a discrete variable. In the warfarin example, one can plot the cumulative count of the gender w.r.t. the age as in the following figure

datxplore_Histogram

Survival curve

(Kaplan-Meier estimator and events mean)

survivalCurve

Links between graphics and combinations of variables

Here is a summary table that shows which plot is used for each combination of X and Y data.

Y X Graphic
Continuous observation Time Spaghetti
Continuous observation Regression Spaghetti
Continuous observation Continuous observation Spaghetti
Continuous observation Continuous covariate Scatter
Continuous observation Discrete covariate Box plot
Discrete observation Time Cumulative histo
Discrete observation Regression Cumulative histo
Discrete observation Continuous covariate Cumulative histo
Discrete observation Discrete covariate Histo. by group
Continuous covariate Continuous covariate Scatter
Continuous covariate Discrete covariate Box plot
Discrete covariate Continuous covariate Cumulative histo.
Discrete covariate Discrete covariate Histo. by group
Event Time Survival curve