It's not. It's often due to under reporting. And sometimes the blatant falsification of data. But you don't really need to do that when only a small percentage of individuals reply to your survey. And thats how you get a high placement rate. You also need to understand that for the hundreds of thousands of CS, IT degrees that are awarded each year only a few thousand jobs exist at the entry level. You see reports of hundreds of thousands of job postings but the vast majority are just repeats of the same listing.