Statistics is the study of patterns in numbers. During your investigations for this course, the two statistical quantities you will most often use are the Mean and the Standard Deviation. The mean or average is what you probably expect. It is simply the sum of all the data, divided by the number of data points. The most common time use of the average in physics is when repeating an experiment many times.
Random errors cause the result to be slightly different each time.
The average of all the experimental results is more accurate than any one measurement, because the random errors should average out to zero. While the average is useful, there is often much more information available in a set of measurements. Suppose you have two procedures for an experiment. You want to know which method gives the better data. Ideally, you can test each method by using each to measure something for which you know the value, or for which you have an expected value.