Hypothesis PDF

HY PO T H E S I S DISCUSSION TOPICS: Definitions of Hypothesis Null vs. Alternative Characteristics of a Well-formulated Hypothesis DEFINITIONS OF HYPOTHESIS  It is a tentative prediction about the nature of the relationship between two or more variables.  It represents an educat...

HY PO T H E S I S DISCUSSION TOPICS: Definitions of Hypothesis Null vs. Alternative Characteristics of a Well-formulated Hypothesis DEFINITIONS OF HYPOTHESIS  It is a tentative prediction about the nature of the relationship between two or more variables.  It represents an educated guess about what will happen in an experiment.  “A hypothesis can be defined as a tentative explanation of the research problem, a possible outcome of the research, or an educated guess about the research outcome.”(Sarantakos, 1993: 1991)  FOR EXAMPLE, Someone might say, "I have a theory about why Jane won't go out on a date with Billy." Since there is no data to support this explanation, this is actually a hypothesis. In the world of statistics and science, most hypotheses are written as "if...then" statements.  FOR EXAMPLE, Someone performing experiments on plant growth might report this hypothesis: "If I give a plant an unlimited amount of sunlight, then the plant will grow to its largest possible size.”  Hypotheses cannot be proven correct from the data obtained in the experiment, instead hypotheses are either supported by the data collected or refuted by the data collected.  DEFINITIONS OF HYPOTHESIS “Hypotheses are single tentative guesses, good hunches – assumed for use in devising theory or planning experiments intended to be given a direct experimental test when possible” (Rogers, 1966). “A hypothesis is a conjectural statement of the relation between two  DEFINITIONS OF HYPOTHESIS “Hypothesis is a formal statement that presents the expected relationship between an independent and dependent variable” (Creswell, 1994). NATURE OF HYPOTHESIS It can be tested – verifiable or falsifiable Hypotheses are not moral or ethical questions It is neither too specific nor too general It is a prediction of consequences NULL HYPOTHESIS (H0 or HN) It usually predicts that there is no relationship between the dependent and independent variables. It assumes that “something”, usually a measure of relationship, “equals zero”.  NULL HYPOTHESIS (H0 or HN) The null hypothesis represents a theory that has been put forward, either because it is believed to be true or because it is to be used as a basis for argument, but has not been proved. It states the exact opposite of what an investigator or an experimenter predicts or expects. ALTERNATIVE HYPOTHESIS (H1 or HA) Predicts the opposite of the null hypothesis. It usually states that there is a relationship between the variables. Usually assumes that there will be an observed real effect in the relationship you are trying to prove.  ALTERNATIVE HYPOTHESIS (H1 or HA) It makes a statement that suggests or advises a potential result or an outcome that an investigator or the researcher may expect. It has been categorized into two categories: directional alternative hypothesis and non directional alternative hypothesis.  EXAMPLE In a clinical trial of a new drug, the null hypothesis might be that the new drug is no better, on average, than the current drug. We would write H0: there is no difference between the two drugs on average.  EXAMPLE The alternative hypothesis might be that: the new drug has a different effect, on average, compared to that of the current drug. We would write H1: the two drugs have different effects, on average. the new drug is better, on average, than the current drug. We would write H1: the new drug is better than the current drug, on average.  CHARACTERISTICS OF A WELL-FORMULATED HYPOTHESIS 1. It must be an empirical statement. - A hypothesis that cannot be investigated using the five senses will be difficult to study using quantitative approaches.  CHARACTERISTICS OF A WELL-FORMULATED HYPOTHESIS 2. It must be plausible. - It must be based on sound logic and should be reasonable or probable. It is difficult to justify spending time and effort doing research and testing hypothesis that are illogical or highly improbable to begin with.  CHARACTERISTICS OF A WELL-FORMULATED HYPOTHESIS 3. It must be specific. - Hypothesis should avoid ambiguity and clearly specify the concepts or variables it covers as well as their expected relationship.  CHARACTERISTICS OF A WELL-FORMULATED HYPOTHESIS 4. It must be formulated in the manner it will be tested. - It should be consistent with how it will be tested. Example, hypotheses written this way: “variables X and Y are positively correlated. An increase in X leads to corresponding increase in Y” are easily determined to be for a correlational research.  CHARACTERISTICS OF A WELL-FORMULATED HYPOTHESIS 5. It must be testable. - There should be a way to investigate whether the hypothesized relationship is true or false. Data needed to test the hypothesis must exist and should be obtainable and the means by which the data can be analyzed should be accessible. EXAMPLE 1:  RESEARCH QUESTION: Do students work better on Monday morning than they do on a Friday afternoon? HA: Students will recall significantly more info on a Monday morning than on a Friday afternoon. H0: There will be no significant difference in the amount of info recalled on a Monday morning compared to a Friday afternoon. EXAMPLE 2:  RESEARCH QUESTION: Does eating breakfast affect student performance? HA: Students who eat breakfast will perform better on a Math exam than students who do not eat breakfast. H0: There will be no significant difference in the performance of students who eat breakfast as compared to students who do not eat breakfast. EXAMPLE 3:  RESEARCH QUESTION: Does using a cellphone while driving affect driver performance? HA: Motorists who talk on the phone while driving will be more likely to make errors on a driving course than those who do not talk on the phone. H0: There will be no significant difference in the number of errors on a driving course for individuals talking on a phone as compared to individuals not talking on a phone. Hypotheses about the relationship between Two Categorical Variables Research Question: Do the odds of having a stroke increase if you inhale second hand smoke? A case-control study of non-smoking stroke patients and controls of the same age and occupation are asked if someone in their household smokes. Variables: There are two different categorical variables (Stroke patient vs control and whether the subject lives in the same household as a smoker). Living with a smoker (or not) is the natural explanatory variable and having a stroke (or not) is