Ch. 8 - Hypotheses

null hypothesis

(Ho) predicts that no relationship exists between variables, and it is subjected to statistical analysis

Identify Sources Or Rationale For Study Hypotheses

1) Theories • Framework as a source • Theoretical or conceptual • Most important source • Propositional statement isolated, tested 2) Personal experience • Induction - Observation - Empirical generalization - Hypothesis • Literature review 3) Previous research studies • Test assumptions • Test hypothesis based on findings

Describe Classifications Of Hypotheses

Hypotheses may be classified as: • simple • complex Hypotheses may be classified as: • research hypotheses • null hypotheses Research hypotheses may be: • directional • nondirectional

Differentiate Nondirectional And Directional Research Hypotheses

Nondirectional Research Hypotheses • Predicts relationship between variables • Does not predict direction of relationship Example: There Is a Relationship Between Serotonin Levels and SIDS • Reasons to Use Nondirectional Research Hypotheses: No theory to base prediction on Previous research findings contradictory Directional Research Hypotheses • Predicts the direction of the relationship Example: People Who Smoke Are More Likely to Develop Lung Cancer Than Those Who Do Not • Advantages: Researcher's expectations clear More precise testing of theoretical propositions One-tailed statistical tests

Compare Null Hypotheses And Research Hypotheses

Null Hypothesis • Ho • Predicts no relationship between variables • Statistically analyzed Research Hypothesis • H1 • Alternative, scientific, substantive, theoretical • States expected relationship between variables • Can be directional or nondirectional Preference for Research Hypothesis: • Clarify study's framework • Demonstrate researcher's critical thinking • Based on theoretical framework Both Null and Research Hypothesis: • Researcher expects no correlations between variables. • Researcher expects no difference between groups being compared

Distinguish Between Simple And Complex Hypotheses

Simple Hypothesis • Bivariate • Relationship between one independent and one dependent variable • Independent variable: cause, first chronologically • Dependent variable: effect Complex Hypothesis • Multivariate • Relationship between Two or more independent variables Two or more dependent variables Both

complex hypothesis

concerns a relationship where two or more independent variables, or two or more dependent variables, or both, are being examined

interaction effect

concerns the action of two variables in conjunction with each other

simple hypothesis

concerns the relationship between one independent and one dependent variable

research hypothesis

or alternative hypothesis (H1); states the expected relationship between variables other names for the research hypothesis are scientific, substantive, and theoretical

nondirectional hypothesis

the researcher merely predicts that a relationship exists; the direction of the relationship is not presented

directional hypothesis

the researcher predicts the type of relationship that is expected; they have several advantages- they make the expectations clear, allow more precise testing of theoretical propositions, and allow the use of one-tailed statistical tests

Discuss The Format For Writing Hypotheses

• A correlational statement • A comparative statement • Statistical analysis

List The Criteria To Be Considered When Formulating A Hypothesis

• Be written in a declarative sentence • Be written in the present tense • Contain the population • Contain the variables • Reflect the problem statement, purpose statement, and research question • Be empirically testable

Critique Study Hypotheses And Research Questions In Research Reports

• Does the study contain a hypothesis or hypotheses? • Is each hypothesis clearly worded and concise? • Is it written in a declarative sentence? • Is each hypothesis directly tied to the study problem? • Is the study framework clearly defined with each hypothesis derived from it? • Does each hypothesis contain the population and at least two variables? • Is each hypothesis stated as a directional research hypothesis? If not, is a rationale given for the type employed? • Is it apparent that each hypothesis can be empirically tested? • Does each hypothesis contain only one prediction?

Research Questions

• In place of hypotheses in some studies • In addition to hypotheses related to other areas of interest concerning topic

Null Hypotheses, Research Hypotheses, and Theories

• Null hypothesis rejected → research hypothesis supported • Research hypothesis supported → theory supported • Research hypothesis not supported → theory not supported

Determine The Types Of Studies For Which Hypotheses Are Not Needed

• Qualitative studies • Single-variable descriptive studies • Methodological studies

Recognize The Use Of Hypotheses In The Testing Of Theories

• Test proposition, not entire theory • Cannot be proved or disproved

Determine The Purposes Of Hypotheses In Research Studies

• lend objectivity to investigations • test theoretical propositions • advance scientific knowledge • guide research design • dictate the type of statistical analysis used • state the expectations about the study