In experimentation, the data collected consist of measurements of one kind or another. These measurements often are numerous and difcult to interpret. Therefore, the researcher’s rst problem is usually to reduce the data to some manageable and meaningful volume, to reduce many numbers to a few numbers, to translate from complexity to simplicity. Graphs and statistics are the most ef- cient and effective techniques for this purpose. People often think of graphs and statistics as making things more complicated. Nothing could be further from the truth. The primary purpose of graphs

This chapter presents (1) samples and populations, (2) the consideration of numbers in statistics, (3) graphical methods of description, and (4) univariate descriptive statistics.