3D effects and exploding pie charts
Avoid design elements that detract from the message you are trying to convey such as 3D effects and exploding slices. These can produce optical effects that make it hard to compare different categories.
For example, in the 3D- exploding pie chart below, the slice representing Alton Towers appears quite a bit larger than that for Pleasureland although there is actually only a 1% difference between the two categories. Also, both slices for Chessington World and Legoland represent 10% but again they appear different sizes due to the 3D perspective. In this example separating (exploding) the different wedges of the pie chart also adds to the difficulty of interpreting the data and estimating the relative size of different sectors.
There are however occasions when the use of an exploding pie chart can enhance the presentation of the data. For example if you wish to highlight information in one category/wedge in particular, or when additional information is provided about a particular category as is shown in the example below.