The Scientific Method

2 Approaches to Studying Science

• “Fishing” expeditions• The scientific method

“Fishing” Expeditions• This type of research is not hypothesis-

driven in the classic sense.

• It includes designing experiments that are geared towards harvesting large amounts of information/data that can be used later to generate hypotheses.

• These types of experiments include techniques like pull-downs followed by MudPIT, microarrays, RNA seq, genome sequencing, and many others.

• No guarantee you’ll get something useful. Any even if you do, you might not know what to do with it. Can be very “hit or miss.”

The Scientific Method

Science is a way of examining and finding order in the natural world. It is a human construct that is formed by dynamic processes that seek to expand our current body of knowledge.

Because all the laws, principles, and theories of biology result from scientific inquiry, it is worth looking into how we perform this type of inquiry, and identifying components necessary for its success.

The Scientific MethodScientific inquiry, a term I use interchangeably with the scientific method, is carried out in five stages:

1. Observations lead to the formation of a research question.

2. The question leads to an educated guess, or hypothesis, about the answer. This can be based on prior research, knowledge, or even intuition.

3. The hypothesis must be tested in a way that allows it to be proven false.

4. Results are interpreted.

5. Conclusions about the value of the hypothesis are made based on interpretation of results. These conclusions are then communicatedto other interested parties.

1. What makes a good research question?

• Can the question be answered?

• Can the question be answered “no”?

• Does the questions specifically address the observations?

2. What makes a good hypothesis?• A hypothesis must be testable.• Assumptions must be defined; “Normally” has no

reference point and contributes nothing to a hypothesis.

• A hypothesis should specifically address the observations you based your research question on.

• You should always generate a null hypothesis, or an alternative hypothesis, that addresses the possibility that the opposite of what you expect to happen might actually happen.

While hypotheses canbe shown to be false, they CAN NOT be proven!!!

You can show support for your theory (hypothesis), but this is not proof, but evidence.

2. What makes a good hypothesis?

3. Testing the Hypothesis• First and foremost, you must have a control, or a

standard of comparison. This is an individual or group of experimental subjects that is not exposed to the treatment being investigated. It serves as a reference to compare with experimental groups that are exposed to your treatment.

• Often the data you seek are obtained by varying one experimental variable, the independent variable, and observing and measuring what change this has on the dependent variable.

• Your results must be repeatable (3x minimum).

The Miller-Urey Experiment: a Case Study of the Scientific Method

Miller-Urey: The Scientific Method

• What question did they address?• What was their hypothesis?• What would be a good null hypothesis?• What experiment did they use to test their

hypothesis? What was their control?• What conclusion did they reach after

obtaining the results from this experiment?

Worksheets and Cabbage experiments

Wednesday there will be a pre-lab quiz