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Scientific experiments are designed to answer questions in biology. Once a question is defined, the first step in designing experiments is to determine the variables—those that are independent, that are defined by the researcher, and those that are dependent—variables that are being measured. All other components of the experiment must remain the same to avoid possible outcomes unrelated to the main variables. After collecting the data, statistical analysis is performed to determine if the hypothesis has been supported or rejected and the results are interpreted to further understand why the data supported the hypothesis. Finally, the data and interpretation are published in a peer-reviewed journal for other researchers to read and build upon.

Experimental Design

Experiments are processes that are carried out to support, refute, or validate a hypothesis. For example, a scientist asks, “How does temperature affect the distance a frog can jump?” and then predicts that cold frogs will not jump as far as room-temperature frogs. To determine if the prediction is true or false, the scientist determines a set of variables. In this experiment, temperature is an independent variable because it is manipulated by the researcher. The experiment would include a control group of frogs at room temperature and an experimental, cold group of frogs. The distance the frogs jump is a dependent variable—a variable being measured with its outcome dependent on the independent variable. To ensure that there are no other variables to confuse the results, all other aspects of the experiment must remain the same, such as the size and sex of the frogs, and the instrument being used to measure distance jumped.

Collection, Analysis and Publishing of Data

Once the experiment is set up, it is carried out under each independent-variable manipulation, and the data are collected. Statistical analyses are performed to determine if the hypothesis is supported or rejected. For example, if it turns out that frogs at room temperature jumped farther than frogs in the cold, then the hypothesis has been supported. To further interpret the data, additional research can be performed to understand the factors that may have impacted the outcome, such as studies on frog physiology. It turns out that when below optimal temperatures, frog muscle fibers cannot produce as much energy, and therefore, cannot jump as far as frogs at warmer temperatures; this information supports the outcome. Once the data and interpretations are completed, they can be published in a peer-reviewed journal for other researchers to read and build upon, and the cycle continues.

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