Scientific Methodology: Background Information, Questions, Research Hypotheses, the Hypothetico- Deductive Approach, and the Test of Hypothesis BIOL January 2016

Overview of Scientific Methodology

1) Background Information Everything already known Everything already known

2) Question Inspired by background info—there is always something as-yet unexplored and unknown Inspired by background info—there is always something as-yet unexplored and unknown

3) Research Hypothesis May (or may not) be true answer to question May (or may not) be true answer to question

4) Test of Hypothesis Designed to attempt to falsify research hypothesis Designed to attempt to falsify research hypothesis May or may not be a controlled experiment May or may not be a controlled experiment

5) Null Hypotheses Symbol: H 0 Symbol: H 0 Predictions of a lack of cause-and-effect in data to be collected Predictions of a lack of cause-and-effect in data to be collected Typically several H 0 ’s for any one research hypothesis Typically several H 0 ’s for any one research hypothesis

6) Statistical Conclusions Each H 0 can either be… Each H 0 can either be… …rejected, or …rejected, or …not rejected. …not rejected. (Notice lack of term “accepted”)

7) Conclusion Do data and statistical conclusions… Do data and statistical conclusions… …support research hypothesis? …support research hypothesis? …refute research hypothesis? …refute research hypothesis?

8) Publication Most commonly in a peer-reviewed journal Most commonly in a peer-reviewed journal Necessary to stimulate the cyclical nature of scientific methodology Necessary to stimulate the cyclical nature of scientific methodology One researcher’s data and conclusions serve as background information, inspiring another researcher’s question and/or research hypothesis One researcher’s data and conclusions serve as background information, inspiring another researcher’s question and/or research hypothesis

Background Information

Three Types A) Personal observation [by author] Cited as: (pers. obs.) May also include author’s unpublished data that relate to the study, cited as: (A. Smith, unpubl. data) the study, cited as: (A. Smith, unpubl. data)

Three Types B) Personal communication [from another researcher] Cited as: (A. Jones, pers. comm. 2001) May also include colleague’s unpublished data that relate to the study to the study

Three Types C) Cited literature Four major types: 1) Peer-reviewed article 2) Book 3) Book chapter in edited volume 4) Unpublished Masters thesis or Ph.D. dissertation dissertation

HANDOUT—Colli et al. 2003

Peer Review Choose a journal Choose a journal Send ms. to editor Send ms. to editor Commonly farmed out to associate editor Commonly farmed out to associate editor Solicits 2-3 anonymous reviews Solicits 2-3 anonymous reviews Ms. returned to author Ms. returned to author A) Accept, following minor revisions based on reviewer comments comments B) May accept, following major revisions C) “Thank you for considering our journal…”

Timeline* Research completed Research completed Ms. submitted to editor a few to several months later Ms. submitted to editor a few to several months later Generally, pre-review by 1-2 colleagues Generally, pre-review by 1-2 colleagues To anonymous reviewers within a month To anonymous reviewers within a month Back to author within a few months of submission Back to author within a few months of submission Final acceptance a few to several months later Final acceptance a few to several months later Publication 6-18 months later Publication 6-18 months later May appear online sooner May appear online sooner *Much faster for Nature, Science, certain biomedical journals, etc.

The Question Inspired by background info Inspired by background info Seeks explanation of phenomenon Seeks explanation of phenomenon

The Research Hypothesis Potentially correct answer to question Potentially correct answer to question (Ergo, potentially incorrect) (Ergo, potentially incorrect) General statement about nature, not one specific to conditions of the test to be conducted General statement about nature, not one specific to conditions of the test to be conducted May be… May be… …strongly suggested by extensive prior theory …strongly suggested by extensive prior theory …reasonable hypothesis based on previous studies …reasonable hypothesis based on previous studies …a stab in the dark …a stab in the dark

Falsification “To prove”: once upon a time, this meant “to test” “To prove”: once upon a time, this meant “to test” Utah proving grounds Utah proving grounds Printer’s proofs Printer’s proofs “The exception that proves the rule” “The exception that proves the rule” Hypotheses can only be disproven with confidence Hypotheses can only be disproven with confidence Confidence that a hypothesis is correct comes with well-designed test(s) that fail to refute it Confidence that a hypothesis is correct comes with well-designed test(s) that fail to refute it

The Hypothetico- Deductive Approach to Science

Deductive Reasoning Using several specific facts to build a general explanation Using several specific facts to build a general explanation Foundation for the Introduction section of a journal article Foundation for the Introduction section of a journal article Discuss background info (lots of known specific facts) Discuss background info (lots of known specific facts) Culminates in formulating research hypothesis (general statement that may or may not explain a phenomenon) Culminates in formulating research hypothesis (general statement that may or may not explain a phenomenon)

Inductive Reasoning Assuming general explanation is true, using it to predict specific outcomes Assuming general explanation is true, using it to predict specific outcomes Foundation for the Methods and Results and lead portion of Discussion Foundation for the Methods and Results and lead portion of Discussion If the research hypothesis is true, in a general way in nature, If the research hypothesis is true, in a general way in nature, Then, one expects certain specific patterns in the data that are to be collected Then, one expects certain specific patterns in the data that are to be collected

The Test of Hypothesis

Data Collection and Analysis Independent Variable: hypothesized cause of some effect Independent Variable: hypothesized cause of some effect Dependent Variable: hypothesized effect of some cause Dependent Variable: hypothesized effect of some cause Hypothesized influence: IV  DV Hypothesized influence: IV  DV

Controlled Experiment Independent Variable: hypothesized cause of some effect Independent Variable: hypothesized cause of some effect Dependent Variable: hypothesized effect of some cause Dependent Variable: hypothesized effect of some cause Hypothesized influence: IV  DV Hypothesized influence: IV  DV Experimental treatment(s): receive(s) IV Experimental treatment(s): receive(s) IV Control treatment(s): do(es) not receive IV Control treatment(s): do(es) not receive IV Control variables: held constant between groups Control variables: held constant between groups

The Advantage of Controlled Experimentation Complete isolation of potential causative variable (the IV) Complete isolation of potential causative variable (the IV) Otherwise, correlation of DV with IV may occur because… Otherwise, correlation of DV with IV may occur because… …IV exerts influence on DV, or …IV exerts influence on DV, or …IV and DV are actually both influenced by a separate variable not under study …IV and DV are actually both influenced by a separate variable not under study