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Hypothesis

A statement of predicted relationship between the independent and dependent variablesExample: Cigarette smoking is related to lung

cancer.

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Hypothesis

Allows theoretical propositions to be tested Suggests an answer to the research question Provides the reader with an understanding of

the researcher’s expectations Guides the research design Dictates the type of statistical analysis to be

used

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Testing a Hypothesis

Advances scientific knowledge Supports or fails to support the tested theory

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Sources or Rationale for Hypotheses

Theories Personal experience Previous research studies

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Generating a Hypotheses

Inductive reasoning Deductive reasoning

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Research Hypotheses

Directional Nondirectional

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Types of Hypotheses

Simple Complex Research Hypothesis Null Hypothesis

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Simple Hypothesis

The relationship between one independent and one dependent variableExample: Birth weight is lower among infants of alcoholic mothers than among infants of nonalcoholic mothers.

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Complex Hypothesis

Two or more independent variables, two or more dependent variables, or bothExample: More postpartum depression and feelings of inadequacy are reported by women who give birth by cesarean section than those who deliver vaginally.

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Interaction Effects

The action of two variables in conjunction with each otherExample: Daily weight loss is greater for adults who follow a reduced calorie diet and exercise daily than for those who do not follow a reduced calorie diet and do not exercise daily.

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Null Hypothesis

May read as “H0” Predicts no relationship Is statistically analyzed

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Research Hypothesis

May read as “H1” States expected relationship between

variables Can be directional or nondirectional

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Directional Hypotheses

States the direction of the relationship Makes a prediction between variables Comes from conceptual/theoretical

frameworks or previous research

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Statistical Analyses

Evaluates the Null Hypothesis Significance level in nursing at or below .05

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Non directional Research Hypotheses

Predicts a relationship between variables Does not predict direction of relationship

Example: There is a relationship between serotonin levels and SIDS.

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Directional Research Hypothesis

Predicts the direction of the relationship Makes researchers’ expectation clear Allows precise statistical testing

Example: People who smoke are more likely to develop lung cancer than those who do not.

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Nondirectional Research Hypotheses

The study has no theory to base the prediction on

Previous research findings may be contradictory

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A Hypothesis Should (criteria)

be written in a declarative sentence be written in the present tense specify the population to be studied reflect the problem statement or the purpose

statement contain all the variables be empirically testable

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Hypothesis Format

A correlational statement A comparative statement

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Hypothesis Format

Promotes statistical analysis of data Uses predictive terms

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Hypothesis

Used to test propositions of a theory Cannot be PROVED or DISPROVED

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Hypothesis

If Null Hypothesis is rejected, the research hypothesis is supported.Example: Null = There is no relationship between studying and test grades.

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Hypothesis

Research hypothesis supported, theory also supported

Research hypothesis not supported, theory also not supportedExample: Research Hypothesis = Those who study get higher test grades than those who do not.

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Hypotheses

Needed when the relationship between variables is being studied

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When aren’t Hypotheses Needed?

in qualitative studies in single-variable descriptive studies in methodological studies

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Research Questions May be Used

in place of hypotheses in some studies in addition to hypotheses related to other

areas of interest concerning the study topic

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Guidelines for Critiquing Hypotheses and Research Questions

Does the study contain a hypothesis or hypotheses? Is each hypothesis clearly worded and concise? Is the hypothesis written in a declarative sentence? Is each hypothesis directly tied to the study problem? If there is a clearly identified study framework, is

each hypothesis derived from this framework?

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Guidelines for Critiquing Hypotheses and Research Questions

Does each hypothesis contain the population and at least two variables?

Is each hypothesis stated as a directional research hypothesis? If not, is the rationale given for the type of hypothesis that is stated?

Is it apparent that each hypothesis can be empirically tested?

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Guidelines for Critiquing Hypotheses and Research Questions

Does each hypothesis contain only one prediction?

If the study contains research questions, are the questions precise and specific?

Do the research questions further delineate the problem area of the study?