How biometrics reliable are biometrics?

• If you have a fingerprint reader on your laptop, you will know that it sometimes works better than others – have you just washed your hands? Used cream? Is your skin dry?
• When you use it and it does not recognise you, this is called a false negative. The fingerprint reader did not recognise you when it should have.
• All biometrics store a certain number of points or readings. Although the biometric is unique, when points are taken, the records created may not be. There have been several problems with finger prints due to this. (For example, the case of DC Shirley McKie in 1997.)
• This is called a false positive. It recognises someone when they are not.
• The more points you use, the less false positives you have. However, the more expensive and difficult it is to handle.
• DNA, and all biological specimens, have a particular problem in that it is difficult to prevent contamination, leading to wrong identifications in some cases.