Boxplts with small amounts of data

[Colin Grayer]

TeeChart 6 boxplots give odd results if there are only a few items of data (less than 4). This may arise when you are displaying boxplots for various levels of a factor, since some levels may not occur often.

If there is only one item of data, most statistics packages display a single horizontal line (the median). I am not exactly sure what TeeChart does, but I am told that it is strange! I have got round the problem by giving Teechart two identical values, which works fine.

If there are 2 or 3 items of data, the usual convention is to display the box with no whiskers. For 2 items, TeeChart nearly does this, but the top and bottom lines are either thick or double, implying that there is a very short whisker. For 3 items the whisker is usually visible - I have got round this by repeating the maximum and minimum values to give 5 items of data. But it still gives the problem of thick or double lines.

[Pep]

Hi Colin,

could you please be so kind to post an example (into the news://www.steema.net/steema.public.attachments newsgroup) with which we can reproduce the problem here and show us which would be the correct results for you ?