Ramachandra

Center= center of a distribution is the point where about half of the observations are on either side.

Spread= The spread of a distribution refers to the variability of the data

1.Larger spread. 2. smaller spread clustered around a single value.

Shape= The shape of a distribution 1.Symmetry 2.Skewness 3.Number of peaks.

Unusual features=Gaps & outliers in distribution

When dotplots are used to compare data sets, they are positioned one above the other, using the same scale of measurement, as shown on the right.The dotplot on the right shows pet ownership in homes on two city blocks. Pet ownership is a little lower in block A. In block A, most households have zero or one pet; in block B, most households have two or more pets. In block A, pet ownership is skewed right; in block B, it is roughly bell-shaped. In block B, pet ownership ranges from 0 to 6 pets per household versus 0 to 4 pets in block A; so there is more variability in the block B distribution. There are no outliers or gaps in either data set.

The back-to-back stemplots are another graphic option for comparing data from two groups. The center of a back-to-back stemplots consists of a column of stems, with a vertical line on each side. Leaves representing one data set extend from the right, and leaves representing the other data set extend from the left. The back-to-back stemplots on the right shows the amount of cash (in dollars) carried by a random sample of teenage boys and girls. The boys carried more cash than the girls - a median of $42 for the boys versus $36 for the girls. Both distributions were roughly bell-shaped, although there was more variation among the boys. And finally, there were neither gaps nor outliers in either group.

With parallel boxplots ( side-by-side boxplots), data from two groups are displayed on the same chart, using the same measurement scale. The boxplots to the right summarizes results from a medical study. The treatment group received an experimental drug to relieve cold symptoms, and the control group received a placebo. The boxplots shows the number of days each group continued to report symptoms.

A double bar chart is similar to a regular bar chart, except that it provides two pieces of information for each category rather than just one. Often, the charts are color-coded with a different colored bar representing each piece of information. To the right, a double bar chart shows customer satisfaction ratings for different cars, broken out by gender. The blue rows represent males; the red rows, females.