What are the two kinds of hypothesis
Published on May 6, 2022 by Shaun Turney. Revised on September 14, 2022. The null and alternative hypotheses are two competing claims that researchers weigh evidence for and against using a
statistical test: The effect is usually the effect of the independent variable on
the dependent variable. The null and alternative hypotheses offer competing answers to your research question. When the research question asks “Does the
independent variable affect the dependent variable?”: The null and alternative are always claims about the population. That’s because the goal of hypothesis
testing is to make inferences about a population based on a sample. Often, we infer whether there’s an effect in the population by looking at differences between groups or relationships between variables in the sample. It’s critical for your research to
write strong hypotheses. You can use a statistical test to decide whether the evidence favors the null or alternative hypothesis. Each type of statistical test comes with a specific way of phrasing the null and alternative hypothesis. However, the hypotheses can also be phrased in a general way that applies to any test. The null
hypothesis is the claim that there’s no effect in the population. If the sample provides enough evidence against the claim that there’s no effect in the population (p ≤ α), then we can reject the null hypothesis. Otherwise, we fail to reject the null hypothesis. Although “fail to reject” may
sound awkward, it’s the only wording that statisticians accept. Be careful not to say you “prove” or “accept” the null hypothesis. In other words, the null hypothesis (i.e., that there is no effect) is assumed to be true until the sample provides enough evidence to reject it. Null hypotheses often include phrases such as “no effect,” “no difference,” or “no relationship.” When written in mathematical terms, they always include an equality (usually =, but sometimes ≥ or ≤). You can never know with complete certainty whether there is an effect in the population. Some percentage of the time, your inference about the population will be incorrect. When you incorrectly reject the null hypothesis, it’s called a type I error. When you incorrectly fail to reject it, it’s a type II error. Examples of null hypothesesThe table below gives examples of research questions and null hypotheses. There’s always more than one way to answer a research question, but these null hypotheses can help you get started.
*Note that some researchers prefer to always write the null hypothesis in terms of “no effect” and “=”. It would be fine to say that daily meditation has no effect on the incidence of depression and p1 = p2. What can proofreading do for your paper?Scribbr editors not only correct grammar and spelling mistakes, but also strengthen your writing by making sure your paper is free of vague language, redundant words and awkward phrasing. See editing example What is an alternative hypothesis?The alternative hypothesis (Ha) is the other answer to your research question. It claims that there’s an effect in the population. Often, your alternative hypothesis is the same as your research hypothesis. In other words, it’s the claim that you expect or hope will be true. The alternative hypothesis is the complement to the null hypothesis. Null and alternative hypotheses are exhaustive, meaning that together they cover every possible outcome. They are also mutually exclusive, meaning that only one can be true at a time. TipBe careful with your words when you report the results of a statistical test in a research paper or thesis. If you reject the null hypothesis, you can say that the alternative hypothesis is supported. On the other hand, if you fail to reject the null hypothesis, then you can say that the alternative hypothesis is not supported. Never say that you’ve proven or disproven a hypothesis.Alternative hypotheses often include phrases such as “an effect,” “a difference,” or “a relationship.” When null hypotheses are written in mathematical terms, they always include an inequality (usually ≠, but sometimes < or >). As with null hypotheses, there are many acceptable ways to phrase an alternative hypothesis. Examples of alternative hypothesesThe table below gives examples of research questions and alternative hypotheses to help you get started with formulating your own.
Similarities and differences between null and alternative hypothesesNull and alternative hypotheses are similar in some ways:
However, there are important differences between the two types of hypotheses, summarized in the following table.
How to write null and alternative hypothesesTo help you write your hypotheses, you can use the template sentences below. If you know which statistical test you’re going to use, you can use the test-specific template sentences. Otherwise, you can use the general template sentences. General template sentencesThe only thing you need to know to use these general template sentences are your dependent and independent variables. To write your research question, null hypothesis, and alternative hypothesis, fill in the following sentences with your variables: Does independent variable affect dependent variable?
Test-specific template sentencesOnce you know the statistical test you’ll be using, you can write your hypotheses in a more precise and mathematical way specific to the test you chose. The table below provides template sentences for common statistical tests.
Note: The template sentences above assume that you’re performing one-tailed tests. One-tailed tests are appropriate for most studies. Frequently asked questionsIs this article helpful?You have already voted. Thanks :-) Your vote is saved :-) Processing your vote... Can you have 2 hypothesis?There is always a minimum of two different hypotheses; Null Hypothesis and Alternative Hypothesis. The hypothesis could be anything, but the most common one is the one I presented below. In the hypothesis testing, we test the hypothesis against our chosen 𝛼 level or p-value (often, it is 0.05).
What are 2 characteristics of a hypothesis?The two primary features of a scientific hypothesis are falsifiability and testability, which are reflected in an “If…then” statement summarizing the idea and in the ability to be supported or refuted through observation and experimentation.
What are kinds hypotheses?Types of hypothesis are: Simple hypothesis. Complex hypothesis. Directional hypothesis. Non-directional hypothesis.
What is null and alternative hypothesis?What are null and alternative hypotheses? Null and alternative hypotheses are used in statistical hypothesis testing. The null hypothesis of a test always predicts no effect or no relationship between variables, while the alternative hypothesis states your research prediction of an effect or relationship.
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