1	What is a mode error? Human-computer mis-communication Mode of operation is misunderstood Data entered or interpreted by human is appropriate for a mode different than the one the computer is in.
2	What is a mode error? A simple example is the case of confusion over UNITS of measure. Here a thermometer display says “32”. Is this cold or hot? It depends on the units of measure.
3	What is a mode error? (I) It is possible for the machine and the user to misunderstand each other. Here the operator understands the measurement to be in Fahrenheit but the device presents the data in Celsius.
4	What is a mode error? (II) Explicit labeling of the units can reduce the possibility of misunderstanding. Here the labeling lets the user understand that the device is reporting the temperature in a different system.
5	What is a mode error? (III) Do we always need the units? Probably not. In many cases, the context shapes understanding. For example, a refrigerator is probably not 32 degrees C!
6	What is a mode error? (IV) The machine can misunderstand too. The operator enters data believing that the machine is in a particular mode. If the machine is in another mode, the result is mode error.
7	What is a mode error? (V) Mode error is very common: You intend to set the cooking time on a microwave oven but end up setting the delay to start of cooking time instead. You intend to set your alarm clock to 6:00 AM but actually set it to 6:00 PM. You intend to use a brush tool in a drawing program but find yourself using the erase tool instead.
8	Do mode errors occur with infusion devices? Yes, this is a common problem. There are many reports of mode errors with these devices.
9	Example of a mode error Here is a portion of a case report from the FDA MAUDE database: ...a programming error involving the hourly rate of an I.V. Meperidine infusion being set for 10 ml/hr instead of 10 mg/hr. The concentration of the medication was 10 mg/ml. This is a MODE ERROR!
10	Are all modes just differences in units? No. Different units are a useful example but there are other types of modes and mode errors. Computer users sometimes type an entry meant for one program window into another window, for example.
11	The term “mode” is used in more than one way Infusion device manufacturers describe “modes” in their devices. Are these the same as the modes of mode error? Those modes are a subset of the modes in the device.
12	How many modes are there? This is a small part of a diagram that maps the modes of a typical infusion device. There are over 5000 distinct states and these reflect hundreds of modes.
13	How can we avoid mode errors? Devices need to use as few modes as possible. Devices need to be designed to make their modes apparent to operators. Operators need to understand the variety of modes that are present in devices. Dialogs between devices and users need to make the current mode prominently visible.