1. Describe a time series design that a researcher might conduct to investigate whether a change occurred in approval ratings of U.S. President Barrack Obama before and after the U.S. government’s...

1. Describe a time series design that a researcher might conduct to investigate whether a change occurred in approval ratings of U.S. President Barrack Obama before and after the U.S. government’s credit rating was downgraded in August 2011.

2. Describe three main sources of bias that can affect results in a quasi-experiment.