Jenny, It looks like they are missing from the census, at least from the transcription. Suggest as a last resort you browse through the census for the area to see if they are there and for some reason have been missed by the transcribers.
Dave

Hi Jenny,

This is the best I could find, but the age of Mary seems wrong.

1871 census - Birchy Field Lane, Oldbury, West Bromwich, Staffs.
James Brazier, 53yrs, Labourer (colliery),(birth column empty).
Mary Brazier, 48yrs, born Tipton, Staffs.
Sarah Brazier, 13yrs, born Tipton, Staffs.

Moira.

Looks like the 13 year old girl was the only one at home. She did not know where her father was born and she guessed her parents ages.
Dave

Hi Moira and Dave

thanks for your replies. It does look like the correct family and it might be as Dave suggested that Sarah gave the information to the best of her knowledge.

Regards

Jenny