Introduction Foundations of Biological Research BIO594

The Scientific Method Observation and description of a phenomenon or group of phenomena Formulation of an hypothesis to explain the phenomena A causal mechanism or a mathematical relation Use of the hypothesis to predict other phenomena, or to predict quantitatively the results of new observations Performance of experimental tests of the predictions by several independent experimenters and properly performed experiments Hypothesis testing Science does not prove anything; it can only disprove

Hypotheses, Models, Theories and Laws Hypothesis - an offered explanation of a phenomenon based upon observational assumptions (“educated guess”) Model - an experimental system in which part of a hypothesis is true; useful for hypothesis testing (i.e., produce facts) Theory - generalizes statement(s) that provide explanatory and predictive powers for phenomena All scientific theories require facts Law - Parts of theories that have a mathematical basis Laws do not provide explanations, only mathematical descriptions of phenomena (e.g., Hardy-Weinberg Law)

Null Hypothesis In hypothesis testing, two mutually exclusive statements must be addressed Drug A will improve the patient’s condition Drug A will not improve the patient’s condition Evaluation of hypothesis testing often relies upon statistical analysis If you have more than two hypotheses for a phenomenon, then you must experimentally address each of them When you’ve disproved all but one hypothesis, you must accept it, no matter how strange it might appear

Electronic Databases UNC Library (databases, interlibrary loan, etc.) Articles A to Z Google Scholar

PubMed gi?db=PubMed gi?db=PubMed Largest biomedical database Maintained by the National Library of Medicine Easily integrated with personal computer database software Electronic Databases

PubMed (cont.) Boolean Operators (MUST BE CAPITALIZED) AND : includes search terms; "t cells" AND interleukin-23 OR : either search term; “t cells” OR interleukin-23 NOT : excludes a search term: “t cells” NOT interleukin-23 Complex search; "t cells" AND hantavirus NOT hantaan Electronic Databases

PubMed (cont) Search Qualifiers au = author: schountz [au] OR “schountz t” [au] dp = date of publication: 2002 [dp] la = language: english [la] ti = words in title: hantavirus [ti] tiab = words in title or abstract: hantavirus [tiab] Use of Parentheses for Complex Searches (virus NOT bacterium) AND diabetes Electronic Databases

Reference Manager Software EndNote Reference Manager These applications allow you to import references from the online databases and will format documents for publication or grant submission. Electronic Databases