Statistics 1 Course Overview Ed Psych 613 Statistics 1 Course Overview

WHAT AM I DOING HERE? Research is a part of our everyday lives. In order to be able to conduct research (master’s thesis doctoral dissertation), we must be able to understand statistics. Even if we just want to be able to understand the research that affects our work, that we see in the media, or just the probability that it will rain tomorrow, we have to understand statistics.

DJ’s Guide to Statistics What frightens you??

DJ’s Guide to Statistics What’s the solution?

Important Info Dr. D.J. Hendricks 231 Walnut St., Morgantown, WV 26505 E-mail: dhendric@mix.wvu.edu or hendricks@jan.wvu.edu Website: http://www.jan.wvu.edu/djhstats

What You Need Textbook: Also Required: Statistics for the Behavioral Sciences, 7th Ed. by Gravetter and Wallnau. Also Required: SPSS Version 16.0 Student Version Basic Hand Calculator—You will need to know how to use your calculator.

How I Grade You will be graded on: Grades assigned based on: Mid-term test = 200 pts. Final Exam = 300 pts. Grades assigned based on: A = 450 – 500 pts. B = 400 – 449 pts. C = 350 – 399 pts.

Stress Reduction Practice Homework will not be graded. Just after the next class, the homework answers for the previous lesson will be put on the website. Do your homework before the next class! Check your answers with the website!!

Introduction and Basic Concepts Lesson 1 Introduction and Basic Concepts

Introduction to Statistics Chapter 1 Introduction to Statistics

Statistics are: A set of methods and rules for organizing, summarizing, and interpreting information.

Data Data are measurements or observations. A data set is a collection of measurements or observations. A score is a single measurement or observation. It also is called a raw score.

Populations and Samples The population is the set of all individuals (events) of interest in a particular study.

Populations and Samples A sample is a set of individuals (events) selected from a population and is intended to represent the population in a research study. A sample usually is obtained through random selection.

Two Forms of Statistics Descriptive statistics summarize, organize, and simplify data from a population or a sample.

Two Forms of Statistics Inferential statistics use samples to make generalizations about the population.

Remember: Population Parameter A parameter is a value, usually a numerical value, that describes a population. Remember: Population Parameter

Remember: Sample Statistic A statistic is a value, usually a numerical value, that describes a sample. Remember: Sample Statistic

Sampling Error …is the discrepancy, or amount of error, that exists between a sample statistic and the corresponding population parameter.

Variables and Constants A constant is a characteristic or condition that does not vary, but is the same for every individual or measurement.

Variables and Constants A variable is a characteristic or condition that changes or has different values for different individuals or measurements.

Scales of Measurement Nominal Ordinal Interval Ratio The word “NOIR” means black in French.

Scales of Measurement A nominal scale consists of a set of categories that have different names. Measurements label and categorize observations, but do not make any quantitative distinctions between observations.

Scales of Measurement On ordinal scale consists of a set of categories that are organized in an ordered sequence. Measurements on an ordinal scale rank observations in terms of size or magnitude.

Scales of Measurement An interval scale consists of ordered categories where all of the categories are intervals of exactly the same size. Equal differences between numbers on the scale reflect equal differences in magnitude. Ratios of magnitudes are not meaningful.

Scales of Measurement A ratio scale is an interval scale with the additional feature of an absolute zero point. Numbers do reflect ratios of magnitude. There is a true zero.

Its All Greek to Me! In statistics, we often use Greek letters as symbols. Specifically, we use Greek letters to indicate a population parameter Latin (regular) letters to indicate a sample statistic.

Its All Greek to Me! Parameters and their statistics indicates a population mean. indicates a sample mean. indicates a population standard deviation. indicates a sample standard deviation.

Its All Greek to Me! In statistics, we use the upper case Greek letter Sigma S to stand for “sum.” It means to add all the scores for a given variable.

Mathematical Rules Do what is inside the parentheses FIRST! Adding a negative number is the same as subtraction. Squaring a negative number yields a positive number. Multiplying a positive by a negative yields a negative, BUT multiplying two negatives yields a positive.

Exercise 1 Designed to introduce you to statistical symbols and to build skills using the summation symbol.

Frequency Distribution Tables and Histograms Chapter 2 Frequency Distribution Tables and Histograms

Frequency Distributions Spelling test scores

Exercise 2 Designed to start you thinking about ways in which you might organize, summarize, and interpret a data set.

Frequency Distributions A Frequency Distribution Table can help us summarize, describe, and understand this data.

Frequency Distributions Helpful Hints— Put data in order before constructing frequency distribution tables or histograms. 0 (zero) is a valid data value!

Frequency Distributions Construct a table that includes the full range of observed values.

Frequency Distributions The frequency ( f ) is the number of times each score occurs in the data set.

Frequency Distributions This is called a frequency distribution table.

Frequency Distributions N is the total number of observations in the data set. It is calculated by summing the frequency ( f ) column.

Frequency Distributions The p column represents the proportion. Divide the f value for each score (X) by N. Ex: 2 / 19 = .105

Frequency Distributions The percent (%) is calculated by multiplying the p column by 100.

Frequency Distributions The cumulative frequency (cf ) is the frequency of all scores at or below a given score.

Frequency Distribution The cumulative percent (c%) is the percentage of all scores at or below a given score.

Frequency Distributions Finding SX from a Frequency Distribution Table.

Frequency Distributions What would you do with these data?

Frequency Distributions Using bins makes arranging this data much easier.

Frequency Distributions Grouped Frequency Distribution Table

Frequency Distributions Use the frequency distribution table to construct a frequency distribution histogram!

Frequency Distributions Frequency distributions can be symmetrical.

Frequency Distributions Frequency distributions can be positively skewed.

Frequency Distributions Frequency distributions can be negatively skewed.

Frequency Distributions