of different subjects of estimation. As a second example, in a study by Dan Ariely, an audience is first asked to write the last two digits of their social security number and consider whether they would pay this number of dollars for items whose value they did not know, such as wine, chocolate and computer equipment. They were then asked to bid for these items, with the result that the audience members with higher two-digit numbers would submit bids that were between 60 percent and 120 percent higher than those with the lower social security numbers, which had become their anchor. When asked if they believed the number was informative of the value of the item, quite a few said yes. Trying to avoid this confusion, a small number of studies used procedures that were clearly random, such as Excel random generator button and die roll, and failed to replicate anchoring effects. The anchoring effect was also found to be present in a study in the Journal of Real Estate Research in relation to house prices. In this investigation, it was established that the 2-year and 9-year highs on the Case-Shiller House Price Index could be used as anchors in predicting current house prices. The findings were used to indicate that, in forecasting house prices, these 2-year and 9-years highs might be relevant. Difficulty of avoiding Various studies have shown that anchoring is very difficult to avoid. For example, in one study students were given anchors that were wrong. They were asked whether Mahatma Gandhi died before or after age 9, or before or after age 140. Clearly neither of these anchors can be correct, but when the two groups were asked to suggest when they thought he had died, they guessed significantly differently (average age of 50 vs. average age of 67). Other studies have tried to eliminate anchoring much more directly. In a study exploring the causes and properties of anchoring, participants were exposed to an anchor and asked to guess how many physicians were listed in the local phone book. In addition, they were explicitly informed that anchoring would "contaminate" their responses, and that they should do their best to correct for that. A control group received no anchor and no explanation. Regardless of how they were informed and whether they were informed correctly, all of the experimental groups reported higher estimates than the control group. Thus,