# PSY201H1 Lecture Notes - Lecture 6: Frequency Distribution, Standard Deviation, Statistical Inference

## Document Summary

You should understand the basic definitions of probability and the underlying assumption of random sampling. Learn to use the unit normal table to find probabilities for specific scores in a normal distribution, and to find the scores that corresponding to specific proportions of a normal distributions. Find percentiles and percentile tanks in a normal distribution. Be able to determine binomial probabilities using the normal approximation to the binomial distribution. Probability is a method for measuring and quantifying the likelihood of obtaining a specific sample from a specific population. We define probability as a fraction or a proportion. The probability of any specific outcome is determined by a ratio comparing the frequency of occurrence for that outcome relative to the total number of possible outcomes. Probability is used to predict what kind of samples are likely to be obtained from a population. Thus, probability establishes a connection between samples and populations.