   < Back DiffTest Page 5 of 8 Next >    ### Set Bounds panel The Set the bounds window is used to set the desired confidence level for the upper and lower bounds in the Confidence bounds panel.

The number in this window selects the degree of risk to accept that the true probability of a correct trial will be greater than the value shown in the upper, rightmost window of the Confidence bounds panel.

For instance, when DiffTest starts, this window contains the number 0.025.  This asserts that a risk of this size (an error probability of 0.025, which can also be expressed as 2.5%, or as 1 in 40) is acceptable. The error that is risked is that the true probability of a correct trial is even greater than the value given as the Upper bound.

The probability of being wrong in the other direction (that is, of the true value being lower than the Lower bound) is also 0.025.  Thus the total risk of error when accepting that the true answer lies between the lower and upper bounds is 0.05 (5%) so confidence in the answer is 95%.

If the number in the Set the bounds window is altered by the user, the calculation and labelling of the bounds change accordingly.

It is possible to set the probability of the upper bound being exceeded to any value from 0.005 to 0.25.  However, only a few of the possible values for confidence bounds are in widespread use.   The most usual values are:

 p 0.005 0.025 0.05 Confidence 99% 95% 90%