ABSTRACT
This chapter examines validation and bootstrap methods to some problems in different fields. Hopefully the sample of studies will convey the message that these methods are very generally applicable and solve many problems which would have been otherwise unsolved or would have resulted in some inferior solution. Since the number of accidents is regarded as high, the crossing is a candidate for modification in order to make it safer. Predicting rain provides some interesting problems and describes some experiences of work with such forecasts. The goal was to produce predictions for a whole area and to display such predictions on maps. Some cost functions are based on statistical information. The danger of using some ready made computer program for contingency tables without noticing the true nature of the data is obvious. When the realistic analysis is complicated, the computer intensive method becomes very attractive.
