Megumi Sui 1
Reliability and Validity
Megumi Sui
Texas A&M University
Dr. Rebecca Schlegel
22 March 2016
Introduction
Two vital concepts that constantly appear in scientific discussions are reliability and
validity. Reliability simply refers to how consis
Psychology 203
Notes Ch. 8
Normal Curves, Probability and Z-Scores
The Normal Curve
3 defining features
Mean, Median, and Mode are equivalent
i.e. not skewed
Perfectly symmetrical
Again, not skewed
Asymptotic
Tails get closer and closer to
the x-ax
Psychology 203
Notes Ch. 7
Hypotheses
An educated guess based on theory and past research
Purpose
Provide benchmark for statistical analyses
Null Hypothesis Significance Testing
SAMPLING ERROR
How close the sample is to the population
Sampling error
Psychology 203
Notes Ch. 6
Reliability and Validity
Independent Variables
The conditions in an experiment
I manipulate
Dependent Variables
The outcome you are investigating
D = data
Issues of measurement scale, reliability, and validity are issues tha
Psychology 203
Notes Ch. 5
Correlation Coefficients
Correlations ask:
How do changes in the value of one variable influence the values of
another variable
Scatterplots
A plot of each set of scores on separate axes.
Scatterplots are valuable because t
Psychology 203
Notes Ch. 4
Graphing Data
Histograms
Histograms allow us to see the distribution of our data
In a histogram, the height of each bar is the number of times each value occurs in
our data set
Distributions can vary in 4 ways
Central tenden
Psychology 203
Notes Ch. 3
Variability
Descriptive statistics
Goal: Organize and describe the nature of the data
2 Types
Measures of central tendency Last chapter
Tell us the typical score
Measures of variability This chapter
Tells us how different
Psychology 203
Notes Ch. 2
Measures of central tendency
First step
Organize and describe the data
Descriptive Statistics
One type of descriptive statistics: Measures of central tendency
A single number that best represents an entire group of
scores
Psychology 203
Notes 1 A&M
2 types of statistics:
Descriptive Statistics
Used to organize and describe data
What is the most common major?
What is the average age?
What is the proportion of males/females?
Inferential statistics
The typical next ste
Study Guide for Second Exam
In addition to practice, practice, practiceHeres a list of the topics weve covered so far that
will appear on the second test to help you organize your studying. It is not meant to be
exhaustive but to give you a handy list of
Psychology 203
Notes Ch. 9
Significance Testing
The basic steps
Step 1: State the Hypotheses.
Null and research
Step 2: Set significance level
Step 3: Compute statistics.
This is the step the varies between chapters.
Step 4: Make a Decision.
Rejec
Megumi Sui, 1
Gender and Aggression
Megumi Sui
Texas A&M University
Dr. Rebecca Schlegel
12 April 2016
Megumi Sui, 2
Introduction
Aggression levels vary for everyone and this study examines if there are any differences
in aggression levels between genders
Megumi Sui 1
The Big Five Personality Traits
Megumi Sui
Texas A&M University
Dr. Rebecca Schlegel
23 February 2016
Introduction
Statistics is the basic foundation of quantitative reasoning in several fields of discipline.
The two main types of statistics
January 27, 2016
Chapter 3 Variability
Variability
o How different the scores are
o Can think of spread or dispersion
o Helps us understand our data
Measures of variability
o Ways of assigning a specific numerical value
o 3 types
Range
Standard deviatio
Chapter 1
January 22, 2016
What is Statistics?
Statistics
o Set of tools and techniques that is used for describing, organizing, and interpreting data
Science has three basic goals
o Descriptions
How do people behave
o Prediction
Identify the factors th
Study Guide
In addition to practice, practice, practiceHeres a list of the topics weve covered so far that will appear
on the first test to help you organize your studying. It is not meant to be exhaustive but to give you a
handy list of the main points w
Study Guide for Final Exam
Chapter 14: Factorial ANOVA
What is it and when do you use it?
Factorial notation system (e.g. 2x2, 2x3)
Main effects vs. interactions
What are they conceptually?
How can you spot them with the means?
How can you spot them in gr
Study Guide-Test Three
Chapter 11: Independent Samples T-Tests
When do you use independent sample t-tests?
Know the steps for executing a t-test and making a decision
Critical and obtained values
Degrees of freedom for independent t
t tables
Interpreting/
Study Guide for Second Exam
In addition to practice, practice, practiceHeres a list of the topics weve covered so far that will appear
on the second test to help you organize your studying. It is not meant to be exhaustive but to give you a
handy list of
Test 4 Review
Covers 16-18+lecture material
22 questions (44 points) 2 problems (6 points)
Regression
Non-parametric tests
o Chi-square
o Sign and binomial tests
Other statistical tests
o MANOVA, ANCOVA, repeated measures ANOVA
o Multiple regression, fact
Test 2 Reviews
20 MC and Math Problems
T-test or Z-test Calculate Effect Size
Chapters 7-12
How to select which type of test
Hypotheses
Null Hypothesis- no difference
Research Hypothesis- there is a difference- may state directionality (correlation)
-One-
Test Selection
Data can come in various forms depending on:
o Number of independent variables
o Number of dependent variables
o One time, or several occasions
o Same or different participants
o Measuring differences in groups or relationships between vari
3/4/11
The one sample t-test
o One sample z-test= one set of data and we want to determine if mean
scored differ significantly from the population mean.
We need population mean and population standard deviation
o We can also use our t-test in this situat
3/2/11
Dependent Samples t-test
o Independent t-tests are used when groups are unrelated
o Dependent samples are used when we are testing the same group on two
different times
Combining the Two
o The dependent test takes into account a baseline but focuse
2/28/11
Independent Samples t-tests
o Also called t-tests between two groups and Students t-test
o Developed in the Guinness brewery in 1908 by Samuel Gosset
o Claude Guinness hired statisticians and biochemists from Oxford and
Cambridge to improve his c
2/23/11
Significance
Any observed differences are due to some systematic influence rather than chance
Adolescents, video games and aggression
o Measure aggressive behaviors following violent video games or non
violent video games
o If we notice differen