Part III Taking Chances for Fun and Profit

1
Part IIITaking Chances for Fun and Profit

• Chapter 7 ? ? ?
• Hypotheticals and You Testing Your Questions

2
What you will learn in Chapter 7

• The difference between samples and populations
• The importance of
• The null hypothesis
• The research hypotheses
• How to judge a good hypothesis

3
What is a hypothesis?

• An educated guess
• Role is to reflect the general problem statement
  or question that is driving the research
• Translates the problem or research question into
  a form that can be tested.

4
Samples and Populations

• Population
• The large group to which you would like to do
  generalize your findings
• Sample
• The smaller, representative group of the
  population that is used to do the research
• Sampling error a measure of how well a sample
  represents the population

5
The Null Hypothesis

• Statements that contain two or more things that
  are equal (unrelated) to one another
• H0 m1 m2
• Starting point and is accepted as true without
  knowing more information
• Benchmark to compare actual outcomes

6
The Research Hypothesis

• Statement that there is a relationship between
  two variables
• Two Types
• Nondirectional -- H1 X1 X2
• Reflects a difference direction is not specified
• Two-tailed test
• Directional -- H1 X1 gt X2
• Reflects a difference direction is specified
• One-Tailed test

7
Hypotheses and Questions

• In psychology experiments reported in scholarly
  journals the form of these questions and/or
  hypotheses varies. For example, let's take two
  fairly simple variables arousal level and test
  performance. First of all, let's contrast an
  experimental hypothesis with a question
• hypothesis I predict that arousal and test
  performance will be significantly related.
• question What is the relationship between test
  performance and arousal?

8
Directional and Non-directional

• Another way of differentiating among experimental
  hypotheses is to contrast directional and
  non-directional hypothesis. A directional
  hypothesis is more specific, the experimenter
  predicts not only that a specific relationship
  will exist, but, further, the direction of that
  relationship
• non-directional I predict that arousal and test
  performance will be significantly related.
• directional I predict that, as arousal
  increases, test performance will decrease.

9
Null Research Hypotheses
10
Differences Between Null and Research Hypotheses
Null Research
No relationship between variables Relationship between variables
Refers to the population Refers to the sample
Indirectly tested Directly tested
Written using Greek symbols Written using Roman symbols
Implied hypothesis Explicit hypothesis
11
Create null hypothesis, non directional
hypothesis, and directional hypothesis for
following

• Mexican Americans and African Americans and
  income
• Fan attendance at 49er verse Raider Games
• Quiz scores in statistics classes of SOCI 15
  verse Math 95
• Whats the best way to be successful in a
  statistics class( need to be a little creative
  for this one?

12
What Makes a Good Hypothesis?

• Stated in a declarative form rather than a
  question
• Defines an expected relationship between
  variables
• Reflects theory or literature on which they are
  based
• Brief and to the point
• Testable include variables that can be measured

13
Glossary Terms to Know

• Hypothesis
• Null Hypothesis
• Research Hypothesis
• Direction Non-directional hypotheses
• One-tailed Two-tailed test
• Population
• Sample
• Sampling error