- errors can be detected by adding
*parity check bits*(検査ビット) to the data - the simplest form of error detection is to add one bit to each
data word to make the total number of 1's even (
*even parity*) or odd (*odd parity*) *Example:**0110111 (7 bits)**10110111 (8 bits, even parity)**1010111 (7 bits)**01010111 (8 bits, odd parity)*

*an odd number of errors can be detected*- the probability of 1 error is more probable than 2 errors
- if
*p*is the probability of one error then*p*^{n}is the probability of*n*errors