Question : Using rand()  to generate data

I am trying to generate test data.  I have one table that has a list of dates, another that has a list of residents.  I want to generate a metric that is 1 80% of the time, and 0 the other 20%.  Presumably, a random generator function needs to be employed.  

Here's what I have:

SELECT D.ActualDay, R.RESIDENT_ID, 1 AS 'Metric'
FROM DIM_DATE AS D, DIM_RESIDENT AS R

Which generates my data except my metric is always 1.  I did try using rand() and got a random number in the metric field, but it was the same number repeated over and over.  I want a stored procedure, which I can run that will populate a table having fields day, resident, metric using the dates from DIM_DATE and the residents from DIM_RESIDENT.

Answer : Using rand()  to generate data

RAND(
CAST( NEWID() AS varbinary )
)