### 2.1 Exploratory Data Analysis

Classical methods of statistical inference depend
heavily at least on the following assumptions:

- The data are outlier-free.
- The data are nearly normal.

In addition, certain statistical techniques
(e.g., multiple regression) require that:

- The relationships of independent variable(s)
with dependent variable are linear.
- Independent variables themselves are not
highly correlated.

The following graphical techniques available in
IDAMS module – GRAPHID – can provide useful insights into the
nature of the data.

- Histogram
- Box and whisker plot
- Scatter plot