Sample survey. A polling organization is checking its database to see if the two data sources it used sampled the same zip codes. The variable if the data source is MetroMedia, 2 if the data source is DataQwest, and 3 if it s RollingPoll. The organization finds that the correlation between five-digit zip code and Datasource is It concludes that the correlation is low enough to state that there is no dependency between Zip Code and Source of Data. Comment.