Psychokinesis is another large component of ESP. Psychokinesis is the ability for a person to use their mind to affect material objects. Holger Bösch, Fiona Steinkamp, and Emil Boller examined many attempts to test psychokinesis (PK), by seeing if participants could influence the fall of dice, and the output of random number generators (Bösch). They cited that there had been three previous attempts to analyze PK that ended with inconclusive results. When trying to test psychokinesis for themselves they quickly realized why the previous test had trouble getting clear results. Throwing dice was not sufficiently random as the participants could manipulate their throw in order to make their results look better resulting in a dice throwing machine being developed. They also realized that there could be errors in how the dice rolls were recorded, opting to take images of each throw to ensure accurate data. There were also issues with normal commercial dice being unevenly weighted due to the number of pits for higher numbers being lighter making higher numbered sides more likely to be rolled. This led to many dice experiments being written off and looked down upon by the scientific community as the data could easily be altered to get favorable results. When the same kind of dice experiments were done with more controlled variables the results no longer showed any significant signs of PK. Diane Ferrari who worked in the Department of Psychology at Princeton analyzed 148 different dice experiments. Across the experiments there were a total of 2,592,817 rolls. In each of these rolls the participant would attempt to mentally influence the roll through the power of psychokinesis. Of these 148 experiments only 69 had accounted for the die face bias present in consumer dice. In the end when accounting for all controls necessary, with the experiments that were left brought the results down to an insignificant level. It was obvious that dice experiments were not able to be controlled enough for the experiments to garner enough data to achieve statistical significance. This meant the hunt for a reliable means to test PK continued.