unrepresentative
adjective /ˌʌnˌreprɪˈzentətɪv/
  /ˌʌnˌreprɪˈzentətɪv/
- unrepresentative (of somebody/something) not typical of a group of people or things and therefore not useful as a source of information about that group synonym untypical
- an unrepresentative sample
 - This early novel is unrepresentative of her work as a whole.