The hypothesis goes at the end of the introduction section, typically in the last paragraph. It appears after you’ve summarized the existing research and identified a gap in knowledge, serving as the natural bridge between “here’s what we don’t know” and “here’s what I set out to test.” This placement follows the standard IMRaD structure (Introduction, Methods, Results, and Discussion) used in most academic papers.
Why It Comes at the End of the Introduction
The introduction of a research paper follows a specific logical sequence, almost like a funnel. The UCLA Writing Center breaks this into four components: you start broad with background on your topic, then summarize what existing research has found, then identify a gap or unresolved problem in that research, and finally state your hypothesis. Each step sets up the next. Your reader needs context before the hypothesis makes sense.
Think of it this way: the introduction mirrors the scientific method itself. Researchers start with what’s already known, notice something that hasn’t been explained or tested, and then formulate a prediction. The written paper follows that same path. By the time a reader reaches your hypothesis, they understand why you’re making that specific prediction and why it matters.
What Comes Right Before the Hypothesis
The sentence or paragraph immediately before your hypothesis should clearly state the gap in existing knowledge. This is the “problem” your research addresses. For example, if previous studies examined a drug’s effects on adults but not on adolescents, you’d note that gap, then present your hypothesis about what you expect to find in adolescents. The hypothesis fills the hole you just pointed out.
Some papers use a research question instead of (or in addition to) a formal hypothesis. In that case, the question takes the same position: end of the introduction, right after the identified gap. Whether you use a question or a hypothesis often depends on your field and research design, but the placement stays the same.
Null and Alternative Hypotheses
In quantitative research, there are actually two versions of the hypothesis. The null hypothesis states that there’s no relationship between the variables you’re studying. The alternative hypothesis states that there is a relationship. For instance, the null might say “there is no association between a medication and psychotic episodes,” while the alternative says “there is an association.”
In most published papers, only the alternative hypothesis (what you actually expect to find) appears explicitly in the introduction. The null hypothesis is implied and becomes relevant in the methods and results sections, where statistical tests determine whether you can reject it. You don’t need to formally write out both in the introduction unless your instructor or journal specifically asks for it.
When Papers Don’t Need a Hypothesis
Not every research paper includes a hypothesis, and this depends heavily on the type of study. Qualitative research, which explores experiences, meanings, or social processes, typically uses research questions rather than testable hypotheses. These questions are often continuously revised as data is collected, which makes a fixed prediction impractical.
Case studies and case series also skip the hypothesis. These papers describe what happened with specific patients or situations and are designed to generate new ideas rather than test predictions. Review articles, which synthesize existing research rather than presenting new data, similarly may not include a hypothesis. If your paper falls into one of these categories, a clearly stated research question or objective takes the hypothesis’s spot at the end of the introduction.
Observational and interventional studies, on the other hand, should have a hypothesis. It guides the research design, determines sample size, and shapes how results are analyzed.
Papers With Multiple Experiments
If your paper includes multiple studies or experiments, you have two options for organizing hypotheses. In shorter papers, you can list all hypotheses together at the end of a single introduction. In longer papers with distinct experiments, each experiment often gets its own mini-introduction with its own hypothesis. This is common in psychology and some areas of biology, where a paper might contain three or four related studies that build on each other.
In either case, the principle stays the same: each hypothesis appears after the reasoning that supports it, never before. A hypothesis that shows up without the groundwork of background research and an identified gap feels arbitrary to the reader.
Where the Hypothesis Appears Again
While the introduction is where you first state the hypothesis, it resurfaces in other sections. In the results section, your findings are presented in relation to what the hypothesis predicted. In the discussion section, you explicitly state whether the results supported or contradicted the hypothesis, and what that means for the broader field. The abstract also typically includes a condensed version of the hypothesis alongside the key findings.
The hypothesis should not, however, first appear in the methods or results sections. Readers expect to encounter it in the introduction so they can evaluate the rest of the paper with that prediction in mind. Burying it elsewhere disrupts the logical flow and makes the paper harder to follow.
A Simple Checklist for Placement
- Paragraph 1 or 2: Broad background and why the topic matters
- Middle paragraphs: Summary of relevant existing research
- Second-to-last paragraph: The gap, problem, or unanswered question in that research
- Final paragraph of the introduction: Your hypothesis (or research question), positioned as the logical response to the gap
Some instructors or style guides ask you to also include your hypothesis in a separate “Purpose” or “Aims” statement right after the introduction. If so, the introduction version can be slightly less formal, with the dedicated statement using more precise language. But in the standard IMRaD format, the last paragraph of the introduction is all you need.