# PSYC 2300 Lecture Notes - Lecture 9: Statistical Inference, Statistic, Statistical Parameter

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Introduction to Statistics

1. Statistics, science, and observations

a. Uses of statistics

i. Organize and summarize information

ii. Justify conclusions

b. Goals of statistical procedures

i. Accurate and meaningful interpretation

ii. Provide standardized procedures

2. Populations and samples

a. Population: set of all individuals of interest in a particular study

b. Sample: set of individuals selected from a population for use in study

i. Usually intended to represent the population

3. Variables and data

a. Variable: characteristic or condition that changes or has different values for

individuals

b. Data (plural): measurements or observations of a variable

c. Datum (singular): commonly called a score or raw score

d. Data set: collection of measurements or observations

4. Parameters and statistics

a. Parameter: a value that describes a population

i. Derived from measurements or individuals in a population

b. Statistic: a value that describes a sample

i. Derived from measurements of individuals in a sample

5. Descriptive and inferential statistics

a. Descriptive statistics

i. Summarize data

ii. Organize data

iii. Simplify data

iv. Examples of presentation

1. Tables

2. Graphs

3. Averages

b. Inferential statistics

i. Study samples to make generalizations about population

ii. Interpret research data

iii. Common terminology

1. Margin of error

2. Statistically significant

3. ß (beta)=slope

6. Sampling error

a. Sample is never identical to population

b. Sampling error: natural discrepancy between a sample statistic and

corresponding population parameter

i. Example: margin of error in polls