When to use dropdown, radio button & check box fields

The general rule of thumb for using these 3 different field types is :

Dropdown fields
- more than 3 options are made available to the form user in a list to select from.
- the options are longer in number of characters than simple YES, NO and N/A answers. In this circumstance a dropdown field can save valuable on-screen room on a Mobile form.
- only 1 of the options listed is to be selected.

Radio button
- no more than 3 or 4 options are made available to select from.
- each option is short in length.
- only 1 option listed is to be selected.
- it is useful to the form user to have visibility on-screen of all the options available.

Checkbox field
- more than 1 option is made available to select from.
- one or more (or all) options can be selected.