The statement "it is often difficult to compare the component parts" is not true of pie charts. A pie chart is a circular chart that is divided into sectors or "slices" to represent the proportion of each category in the data being displayed. It is an effective way to display the relative sizes of different categories, as each slice represents a percentage of the whole. However, it may become difficult to compare the sizes of small slices or slices with similar percentages. Therefore, it is recommended to use pie charts only for simple data sets with a few categories.