BIO 101 LAB- The Scientific Method

Step 8: Analyze the data.

Data are compiled and interpreted in order to determine whether the null hypothesis is supported or falsified. Statistical methods are often employed to help interpret data. Ideally, analysis will lead to a conclusion. That is, either accept or reject the null hypothesis.

Step 5: Define the experimental treatments. In this experiment, the experimental treatments are the defined test groups.

For example, one group gets drug A alone; one group gets drug B alone and one group gets A and B together.

Step 9: Repeat the Process Using a More Refined Experiment

For example, suppose that results support the null hypothesis (i.e. the drugs in combination have no increased effect on lowering blood pressure). A new experiment may be designed to test a different hypothesis. For example, perhaps drugs A, B and C may work in combination to lower blood pressure.

Step 3: Make Predictions about results in order to design an experiment.

For example, you predict that treatment using the two drugs will lower blood pressure more than using either drug alone. At this point you may begin to design the details of your experiment. You determine that you will need at least three experimental groups.

Step 6: Formalize actual test procedures. This has the effect of reducing bias

For example, you screen a large group of individuals that have high blood pressure but are otherwise healthy. Next, you assign individuals to specific groups for testing so that each group is fairly equal in terms of age, health etc. This has the effect of reducing bias. Additionally, a control group is set up and gets no drug or a placebo.

Step 1: Make observations

You observe that drugs A and B used independently lower blood pressure levels and you question whether giving these two drugs together may lower blood pressure even more than using the two drugs alone.

Additionally, you may want to establish a __ treatment group which receives either no drug or a placebo but otherwise are treated the same as the experimental treatment groups.

control

Variables held constant between the different treatments are called __ variables

controlled (standardized)

Step 2: form a hypothesis A __ is tentative explanation based on acquired knowledge on the subject

hypothesis

Step 4: Define variables. The factor that is manipulated (changed) in the experiment is called the __ variable. The factor that shows some response to the manipulation of the experiments (or what is measured) is called the __ variable

independent; dependent

The scientific method requires that the hypothesis be formulated so that it can be proven false. Therefore, a null hypothesis must be formulated. The null hypothesis predicts what would happen if the experimental treatment has __ effect. That is, a hypothesis can never be proven 100% true; the hypothesis can only be suggested to be true if the null hypothesis is __

no; rejected For example, the null hypothesis in this case may be that these two drugs, used in combination, will not have a different effect on blood pressure compared to either drug used alone.

One commonly used statistical-based analysis method is the Chi-square. This method allows you to accept or reject the null hypothesis at a certain level of significance. For your experiment, you will calculate a p-value. This p-value will allow you to determine the statistical significance between your results. In biology, a p-value < 0.05 is the typical level where results are considered significant. If your calculated p-value is < 0.05 the null hypothesis will be __. If your calculated p-value is > 0.05, your results are considered not significant and the null hypothesis is __

rejected; accepted

The __ __ is a systematic and objective method for understanding how the natural world works. The scientific method proceeds through a standardized series of steps.

scientific method