In academic writing, one distinction to draw is between argumentative papers and empirical papers. Argumentative papers tend to come from the humanities, while empirical papers usually appear in the sciences. (The social sciences display a mix of argumentative and empirical papers, and sometimes include single papers that display both argumentative and empirical elements.)
An argumentative paper takes a position on an issue and supports that position with evidence and analysis. An empirical paper reports research based on observations or experiments. In other words, an argumentative paper is often about the proper interpretation of evidence (facts, data, information) that is already known about, while an empirical paper is usually about the collection of new evidence that then needs to be interpreted.
Thus, an empirical paper (1) poses a question that can only be answered by gathering information not currently available to the researcher, (2) gathers that information in some controlled way, and then (3) interprets that information.
Cosmetically, one difference between argumentative and empirical papers is the style in which each is written. Argumentative papers can come in MLA, Chicago, or APA style. Empirical papers usually appear in APA style.
More substantially, perhaps the biggest difference between an argumentative and an empirical paper comes in the organization of each. An argumentative paper is usually structured according to introduction, body, and conclusion – that is, an introduction that states a thesis, a body that supports the thesis, and a conclusion that considers the implications of the thesis. In contrast, an empirical paper is usually structured according to introduction, method, results, and discussion.
In other words, empirical papers follow the so-called scientific method. Observations are made; a hypothesis is developed based on those observations; experiments are conducted to test the hypothesis; and those experiments are interpreted to consider the truth of the hypothesis.
As such, an empirical paper is a record of the research process: research and writing occur at the same time. You make an observation, and you write down what that observation is. You generate a hypothesis, and you write down what that hypothesis is. You conceive an experiment, and you write down what that experiment is. You conduct that experiment, and you write down what the results were. And you interpret those results, and you write down what your interpretations are.
In contrast, when writing an argumentative paper, research and interpretation all occur before the first word of the paper is written. An argumentative paper is not about discovery, as an empirical paper is; an argumentative paper is about persuasion.
The only thing that needs to occur before you start writing an empirical paper is to make an observation of something that is peculiar or needs to be explained. Once this observation has been made, you can start writing your paper, beginning with your introduction.
Empirical papers may use quantitative analysis or qualitative analysis. Quantitative research generates numerical data and seeks to establish causal relationships between two or more variables. Qualitative research objectively and critically analyzes behaviors, beliefs, feelings, or values with few or no numerical data available for analysis.