The way to determine whether or not a sample is statistically valid is by knowing how the sample was collected. Scientific sampling requires that each sample be taken by specific methods. Whether the method is by time, age, race, etc. some form of standard criteria must be met by the sample. If any of these methods or criteria is not met, then the sample was not taken scientifically. It
. should not be considered in any statistic. The key to sample taking is standards.
