Posted by Donny on .
How can you determine if you are using a two tailed test vs a one tailed test? For example, for the below, which test would I use?
Based on this data, at α =.01, can we conclude that the proportion of democrats who favor “junk food" tax is more than 5% higher than proportion of republicans who favor such a tax?

Statistics/Math Please Help 
PsyDAG,
For onetailed test, you are only looking for deviation in one direction, indicated by your alternative hypothesis.
Ho: a = b
Ha: a > b or a < b
For a twotailed test, you are just looking for any difference.
Ho: a = b
Ha: a ≠ b
I hope this helps.