Explain the uses and limitations of (published information/data )

This really stems from my free lectures on the second chapter of our lecture notes. Using published information rather than collecting the data ourselves is likely to be faster and cheaper. However the main problems are checking that the data was collected for the purposes we want to use it for (i.e. that it is relevant for the decisions that we want to make), that it is up-to-date, and that it is reliable. As a basic example of this, suppose we are concerned about the level of inflation. We can look up published government statistics giving the rate of inflation. These may be reliable but if they are just showing the average level of inflation then they might not be of much use to us because the costs our business incurs might be inflating at a different rate from the average rate for everything.