SUNY College at Buffalo
Sociology 301: Social Statistics
Study Guide for Exam #2
Dr. ZHANG Jie
**Chapter 4
Measures of central tendency
Measures of variability (all formulas)
range
mean deviation
variance
standard deviation
The meaning of variability
The meaning of standard deviation
The standard deviation in normal distributions
**Chapter 5
Probability as the cornerstone of decision making
The meaning of probability
The range of probability
Calculation of probability
Probability distribution
Normal distribution
Areas (% of cases) under the normal distribution
The z score
The meaning of z score
Table A in Appendix C
Obtaining percentile ranks from the z score
**Chapter 6
Sample and Population
The relationship between sample and population
Sampling methods
Nonrandom sampling (convenience sampling)
Random sampling: every case has the same chance to be selected)
Sampling errors
Margins of error in description
The sample mean
The population mean
Comparing population and sample
The relationship between the sample size and the the standard error
Confidence intervals
68% z = 1
95% z = 1.96
99% z = 2.58
The t distribution (Table B of Appendix C)
The usefulness of the t score
The relationship between t and z
Degree of Freedom (df)
The meaning of df
The relationship between df and sample size