Define each of the following terms as you are responding to the questions. I am looking for more than a simple definition or cryptic response. What are your thoughts. Please provide references and real world example if possible.

1. What is the difference between mean absolute deviation (MAD) and mean squared error (MSE)?

2. What are reasonable criteria for selecting one time-series method over another?

3. Although lower inventories and a just-in-time approach receive considerable attention in the business media, some organizations prefer high levels of inventory. Why would they want to hold a large inventory?

4. What is ABC analysis and how does it work?