How to read the primary literature

How to read the primary literature

The goal:
"Read not to contradict and confute, nor to believe and take for granted...but to weigh and consider."
Francis Bacon

Your role in reading the primary literature is to independently evaluate the data. Do you agree with the author's interpretation? Practicing scientists often get ideas for their own experiments from reading the published data from a different perspective. Perhaps the authors have been blindsided by their own particular history, and cannot see some alternative interpretation of their data. To be an independent evaluator, you must be careful not to be influenced by the authors' viewpoint. Consequently, I try to avoid the abstract and discussion section until I have thoroughly evaluated the data from my own point of view.

How to:
The following is a synopsis of how I approach reading and analyzing a scientific paper.

Step1: Read the introduction section of the paper.
After reading this you should be able to write down the answers to the following questions.

a. What is the question that the authors seek to address in the paper?
b. Why did they want to address this question? What is the background that led up to this paper and why is this work important for us to understand?
c. What do they claim they found out?

Step 2: Read the Results section.
The Result section will be organized around specific questions, and the experiments will be designed to answer those questions. Skip the methods section for right now. You can refer back to the methods as you examine the data for each experiment.

Examine each figure in turn. For each figure you should be able to identify what question was addressed in this experiment. What was the hypothesis? What result did they expect if their hypothesis was correct?
Your next job is to understand how the experiment was done. If you do not understand the method from the figure legend, look it up in the methods section. If you still do not understand the method, look it up in your textbook to get some background.
Your next job is to understand the controls. Experimental data only have meaning in the context of control data. The controls are what allow you to exclude other interpretations of the data. What are the controls in this experiment? Why are they included? What do the data on the controls tell you?
Now you can examine the data for the experimental question. Try to interpret this data without looking up the authors' interpretation in the discussion. What do you think the data mean? Later, when you are all done, you can read the Discussion and see whether you agree with the authors' interpretation of their data or not. If you read the Discussion first, it is very difficult to have an independent view of the data.

After reading the Results section. you should be able to answer the following questions about each figure:
1. What was the question?
2. How did they do the experiment?
3. What is your interpretation of the control data?
4. What do the experimental data show? Are there alternative interpretations?

Step 3: Read the Discussion
Only-ONLY after you have struggled to do step 2, should you do step 3. Otherwise you bypass the intellectual effort to think independently and you loose much of the opportunity to learn. Once you have read the discussion, you should be able to:
1. Summarize the evidence they marshall for their particular interpretation of the data.
2. What other papers have cited results that support or refute their view of the process they are studying?
3. What questions remain to be addressed? How will they likely be approached?