Dependent Samples t-Test
Practice Problems
Recap of Last Class
A research design that involves dependent samples is one where the observations from one sample are related in some way to those from the other. Before vs after (repeated measures) Or two mat
March 8, 2010 INTRODUCTION TO HYPOTHESIS TESTING
#1 #2
List the five steps of hypothesis testing. When a result is significant, explain why is it wrong to say the result "proves" the research hypothesis? For each of the following, (a) say what two populat
March 29, 2010 The t Test for Independent Means
Multiple-Choice Questions #1- A distinguishing feature of the t test for independent means is: a) dependent populations are treated as if they are unrelated. b) The difference between the means of the two in
Z-Test
Summary: 5 Steps of Hypothesis Testing
1) Restate the question as a research hypothesis and a null hypothesis about the populations. 2) Determine the characteristics of the sampling distribution. 3) Determine the level of significance (), and there
Introduction to Hypothesis testing and 1-tailed vs. 2-tailed tests
Chapter 17
Scientific Method
Modify Hypothesis Establish theory based on repeated validation of results
Observe natural phenomena
Formulate Hypothesis
Test hypothesis via rigorous experime
Sampling distributions and Standard error
Chapters 9 & 11
Sample vs. Population
Focus will now shift to sample means, rather than individual scores. Population: Complete set of individuals, objects, or scores that the investigator is interested in studyi
Z-Scores
Z score is a number that is commonly used to convey the relative position of a data value in the data set. The z-score is obtained by subtracting the mean of the data set from the value and dividing the result by the standard deviation of the da
Recap of Last Class
Steps to Calculating Pearson r Correlation and Causation Factors Influencing Pearson r Prediction
Questions?
1
Chapter 8
Correlation and Prediction
Recap: Correlation vs. Prediction
When a bivariate trend is reasonably linear, a li
Recap of Last Class
Concepts of Correlation Scatterplots Patterns of Correlation Questions?
1
Chapter 7
Correlation coefficients
Concepts of Correlation
Degree of Relationship
Low or No Relationship
Medium Relationship
High or Perfect Relationship
Negati
Recap of Last Class
Z-Scores Steps for Finding Percentages from Scores Steps for Finding Scores from Percentages Practice Problems
Questions?
1
Chapter 6
Relationships between two or more variables: Diagrams and Tables
Association Between Variables
Wh
Recap of Last Class
The Normal Distribution Area Under the Curve Scores Relative to the Mean and Standard Deviation Z Scores Approximation Rule Normal Curve Table
Questions?
1
Chapter 5
Z Scores
Standardized Scores
Relative Frequency
Z Distribution Mean
Recap of Last Class
Measures of Central Tendency The Mean The Mode The Median Variance
Questions?
1
Chapter 5
Standard deviation and Z-scores
Problem
A spread measure should have the same units as the original data. E.g., weight of students - variance
Z-Test and Confidence Intervals (Estimation)
Hypothesis Testing vs Estimation
For some problems, hypothesis testing is inappropriate and estimation is the only relevant approach. Example: The manager from the university bookstore wants to know how much m
Decision Errors, Effect Size and Power
Decision Errors
Errors that can happen during the hypothesis-testing process . Decision errors are situations in which the right procedures lead to the wrong decisions. Decision errors occur because in hypothesis-te
Calculating Statistical Power
Examples
1
Example 1
The mean of a population (M2) is 200, with a standard error of the mean of 6. The mean of a sample ( 1) is 208. Significance Level, =0.05, 1-tailed. Step 1: 1=208, SDM=6, 2=200 Step 2: 5% significance le
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PSYC 315 - Assignment 1
Descriptive Statistics
The following data set is comprised of data previously collected across several Statistical Analysis 1
(PSYC 315) sections. The data pertains to the students studying habits and final grades. The dat
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PSYC 315 - Assignment 3
Correlation
Use the SPSS data file A3_Data.sav posted on Moodle to complete the assignment.
To avoid losing points be sure to TYPE your answers, to ROUND final answers to 4 decimal
places (unless otherwise specified), and
Recap of Last Week
Descriptive vs. Inferential Statistics Population vs. Sample Parameter vs. Statistic Independent vs. Dependent Variable Qualitative vs. Quantitative Variable Discrete vs. Continuous Variable Levels of Measurement
1
Recap of Last Week
L
Recap of Last Week
Frequency Distribution Graphs Bar Graphs Histograms Polygons Shape of Frequency Distribution Graphs
Questions?
1
Chapter 3
Describing variables numerically
Averages, variation and spread
The Mean
The Mean is a measure of central tend
Recap of Last Class
Ungrouped and Grouped Frequency Tables Frequency Percentage Relative Frequency Cumulative Frequency Cumulative Percentage Guidelines to Creating Class Intervals Real Limits Percentile Ranks and Scores
1
Exercises on Scales of Measurem
Review for Final Exam
Steps of Hypothesis testing for major procedures
Test: Z Test t-test (one sample) t-test (two sample) INDEPENDENT Null and Alt. Hypothesis t-test (two sample) DEPENDENT Null and Alt. Hypothesis
Step 1: Null and Alt. Hypothesis Step 2
Independent Samples t-Test
Practice Problems
Example 1
A psychologist prepares a list of 40 pairs of nouns. 2 groups of 10 participants are obtained. Group 1 is given 5 minutes to memorize the list, and are also told to form mental images of the words. G
Dependent Samples t-Test
Or Two-Sample Dependent t-test Chapter 12
From One Population M to Two Population M
The focus so-far has been on making inferences about a single population from a single sample. However, most of the time we will obtain two sampl
March 8, 2010 1) Read each of the following statements and indicate if it is true (T) or false (F). a-A type II error occurs when you fail to reject a false null hypothesis. b-If the null hypothesis s in fact true, alpha is the probability that we will in
March 8, 2010 Power and Effect Size Objectives of the exercises: I To understand the logic of hypothesis testing and associated terminology II To understand the concept of Power (the probability of getting significant results if the research hypothesis is
January 20, 2010 Exercises on Z scores 1. Suppose the number of clients seen in any given week by full time psychotherapists in a particular city is normally distributed with a mean of 15.3 and a standard deviation of 2.8. a) A therapist who is in the top
Answers for exercises on Z scores
1. a) From normal curve table, top 5% (45% between mean and Z score) begins at 1.64 (or you can use 1.65). Thus, the corresponding raw score is X = (Z) (SD) + M = (1.64) (2.8) + 15.3 = 19.89. b) From normal curve table, b
ANSWERS The Distribution of Sample Means. Introduction to Hypotheses Testing 1. A company embarks on a new program to boost morale and reduce the amount of absenteeism. The company has recorded an average of 10.5 absences per employee per year with a stan
Answers #1 Step 1 = Restate the question as a research hypothesis and a null hypothesis about the population. Step 2 = Determine the characteristics of the sampling distribution. Step 3 = Determine the cut-off sample score on the sampling distribution at