1. Numbers are one of many tools researchers use to collect data.
2. From the raw data collected, researchers compute the descriptive statistics that convey essential summary data of the dataset as a whole.
3. The normal curve is a theoretical distribution in which the majority of cases peak in the middle of the distribution, with progressively fewer cases as one moves away from the middle of the curve.
4. In normal distributions, one side mirrors the other; the curve is symmetrical.
5. In positively or negatively skewed distributions, the curve is asymmetrical.
6. Frequency distributions and polygons are the first step in analyzing a set of scores for one variable.
7. Descriptive statistics-number of cases, central tendency, and dispersion-are summary information about the dataset for one variable.
8. The number of cases is the number of data points.
9. Measures of central tendency-mean, median, or mode-reflect different types of average or typical data.
10. Measures of dispersion-range and standard deviation-provide a description of the variability of the data.
11. Researchers also use frequencies and percentages to describe their data.
12. Data may be calculated by hand, or with the help of a spreadsheet or statistical program.
13. Researchers are responsible for the results and their interpretations, even if an expert helps them in this aspect of the research process.
