Pictographs are graphic illustrations of statistical data. They use pictures or symbols to represent data. A key is necessary for the understanding of a pictograph.They are not only easy to read but can be visually appealing too. They help in making abstract notions more concrete. They are best used for comparison when the variation or difference in data is large.
For their simplicity of projecting data with the help of symbols or pictures, they are easy to understand. For these reasons, they are good to use especially while addressing a young audience or even in mass media.
However, it is important to draw an accurate picture, as an incorrect picture increases the chances of misrepresenting data or conveying the wrong impression.
Sometimes, it's very simplistic style may make it less desirable for usage. Also, it is difficult to quantify partial icons. The other limitation while using a pictograph is that it is best used only when it is limited to 6 categories or less.