BISC 313 Lecture Notes - Lecture 2: Statistical Hypothesis Testing, Dependent And Independent Variables, Treatment And Control Groups
1 Nov 2017
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Sometimes experiments are difficult or impossible to perform. All methods start with a hypothesis--an informed, logical, and plausible explanation about the natural world seek to explain observed phenomena. Independent variable- the factor that is manipulated or differs. Treatment group- individuals identical to the control but pertaining to the independent variable. Have permeable skin, can easily be susceptible to pollutant molecules. They"re biological indicators- they are some of the first to show effects from environmental problems. Hypothesis: parasitic infections are causing amphibian deformities and declines. Observational field study: surveyed ponds to relate frog deformities with the parasite"s host snail. Controlled experiment: tested observation by exposing tadpoles to different levels of the parasite ribeiroia in the laboratory. Hypothesis: parasites contribute to frog deformities and declines. Rationale: parasite uses larval amphibians for hosts, are common in streams where the deformities are observed, and form cysts on hosts. Predictions: amphibians with parasites will have increased deformities and increased parasite load decreases surviorship.
