People often ask about the advantages and disadvantages of biometric systems (those recognising physical attributes of a person, such as fingers, hands, faces, irises, voices, etc). The key advantage is that peoples’ physical features cannot be lost, misplaced or stolen as easily as cards, and you can thus be certain that the right person is clocking.
The key disadvantages are speed of clocking (generally slower with biometric readers than cards) and acceptability: sometimes staff are wary of the “big brother” aspect of biometric recognition, even though no fingerprints or photographs are stored, but rather just certain measurements of the relative location of key features, which become a long number representing those features, and from which it would be totally impossible to re-generate an image.
Also, since the recognition/validation time is much longer than the time to read and validate a card, staff may prefer the faster reader, so more readers may be required to avoid long queues building up at the reader. Equally, if an employee doesn’t want to co-operate, he can always find ways of making it not work, whereas with a card system (especially a proximity card system), it is virtually impossible for it not to work.
Note: If some of your staff have problems with clocking, fitting a security camera can allow you to ensure the right person is clocking (in the case of using cards) and that (for biometric readers) the equipment is being used properly. If you don’t want to do that, just being present at the reader from time-to-time will allow you to observe whether there are genuine problems or not.