About the Scientific Method:
- Let's talk about the scientific method.
- You will use the scientific method for all of the Microbiology 20 labs.
- Let's start with watching my (less than) 3 minute video on the scientific method:
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Clarification -
In the video, we use the terms "independent variable" and "dependent variable". Remember that the dependent variable always depends on the conditions that you can change (independent variables). The dependent variable in the video above is plant growth. Plant growth depends on various conditions (light, nitrogen, time). Any of the various conditions are independent variables. -
The scientific method is a set of techniques that serves to answer scientific questions. It involves the following systematic method of inquiry:
Hypothesis:
A simple yet specific statement of the effect of the treatment. HOW TO WRITE A HYPOTHESIS: “The [treatment] will [have a specific effect] on [parameter of interest] compared with the [control]. For example: Adding sugar (dextrose) to the agar used to grow plant cells in vitro will make them grow faster.
Experiment:
The hypothesis is tested by designing and performing an experiment, which often involves testing effects of a treatment. A well-designed experiment will include randomly assigned groups and unbiased measures of the outcome. The experiment often includes the following:
- Treatment: Sugar
- Control: The standard of comparison. All conditions are identical to those of the treatment group, except the treatment itself. In the example above: not adding dextrose to the agar
- Dependent Variable: The variable being measured. Ex: plant cell growth
Conclusion:
Either validation or invalidation of the hypothesis based on the results of the experiment. Analysis of the effect of a treatment centers around statistical significance (are the groups statistically different?), biological significance (is the difference biologically relevant?), and scope of inference (was the experiment only algae?). Repeated verification of a hypothesis may result in a theory. Eventually, the theory may become a law, or principle.