CHAPTER 16 STUDY GUIDE

Chapter 16: Descriptive Statistics
Definition- Statistics used to describe the basic features of the study population. Main concepts include: Frequency Distributions, Central Tendency, Variability, and Risk Indexes.
Levels of Measurement
Nominal- assigning numbers to classify categories. For example, 1 for blood type A and 2 for Blood type B
Ordinal- classification based on ranking. For example, 1 –Poor, 2-Good, 3-Excellent
Interval- Interval scales that assume similarity in the difference between values. For example, 20-40 degrees and 50-70 degrees.
Ratio- Measurements that give rank on an attribute, exact interval, and meaningful attribute. For example height.
FREQUENCY DISTRIBUTIONS -Arrangement of values (x) from lowest to highest and the number of times each value is attained (f).
A set of data is described using 3 characteristics;
Shape of Distributions- Displayed in Graphs using histograms and polygons whose shapes describe data as either skewed, positively skewed, or negatively skewed.
Central Tendency- Use a single value to represent a data set.
Statistical methods used;
Mode- Most frequent occurring value. Used to quickly determine a popular score.
Median- Value at the midpoint. Preferred for a skewed distribution.
Mean- Average value. Majorly used in interval and ratio measurements
Variability- How dispersed or spread distribution is.
Statistical methods used;
Range- Highest value minus lowest value. Mainly used as an unrefined descriptive inde…