What is the difference between a hypothesis and an alternative hypothesis?

Jackson Taylor | 2023-06-17 07:12:22 | page views:1906
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Julian Martinez

Works at the International Finance Corporation, Lives in Washington, D.C., USA.
As a domain expert in statistics, I specialize in the interpretation and application of statistical tests and hypotheses. I'm here to provide a comprehensive understanding of the concepts you've inquired about.
To begin with, a hypothesis in statistics is a proposed explanation for a phenomenon, which can be tested through empirical research. It's a statement that can be supported or contradicted by evidence. In the context of hypothesis testing, there are two primary types of hypotheses: the null hypothesis (H0) and the alternative hypothesis (H1 or Ha).

The null hypothesis is a statement of no effect or no difference. It is a default position that assumes there is no significant relationship between the variables being studied. It is the hypothesis that researchers attempt to reject through their statistical tests. The null hypothesis is often symbolized by H0 and is always written as an equation of equality. For example, in the context of a two-sample t-test, the null hypothesis might state that there is no difference in the means of two groups (μ1 = μ2).

On the other hand, the alternative hypothesis is a statement that there is an effect or a difference. It is what researchers are typically interested in supporting with their study. The alternative hypothesis is represented by H1 or Ha and is formulated to contradict the null hypothesis. It can be one-sided (directed) or two-sided (non-directed), depending on the nature of the prediction. In the same example of a two-sample t-test, the alternative hypothesis might posit that one group's mean is greater than the other (μ1 > μ2) or that there is a difference between the means, without specifying direction (μ1 ≠ μ2).

Here are some key differences between the null and alternative hypotheses:


1. Position of Default: The null hypothesis is the default position that no effect is present. The alternative hypothesis is the position that an effect is present.


2. Role in Testing: The null hypothesis is what is tested and potentially rejected in favor of the alternative. The alternative hypothesis is not directly tested but is the preferred outcome if the null hypothesis is rejected.


3. Statistical Significance: If the test results show that the null hypothesis is unlikely (based on a predetermined significance level, such as 0.05), the researcher rejects the null hypothesis and may conclude that the alternative hypothesis is supported.


4. Formulation: The null hypothesis is typically formulated as an equality (e.g., no difference), while the alternative hypothesis can be formulated as an inequality (e.g., a difference exists).


5. Research Predictions: The alternative hypothesis aligns with the researcher's predictions or expectations, whereas the null hypothesis represents the absence of the predicted effect.


6. Risk of Error: There are two types of errors in hypothesis testing: a Type I error (rejecting a true null hypothesis) and a Type II error (failing to reject a false null hypothesis). The significance level (alpha) is set to control the risk of a Type I error.

7.
Directionality: The alternative hypothesis can be one-tailed (predicting a specific direction of the effect) or two-tailed (predicting an effect in either direction).

In sum, the two-sample (independent samples) t-test is a choice between two possibilities; a null hypothesis and an alternative hypothesis. The null hypothesis is that the researcher's prediction is not true. The alternative hypothesis is that the researcher's predicted difference is true.

Now, let's proceed with the translation into Chinese.


2024-04-21 10:42:35

Isabella Gonzales

Studied at the University of Tokyo, Lives in Tokyo, Japan.
In sum, the two-sample (independent samples) t-test is a choice between two possibilities; a null hypothesis and an alternative hypothesis. The null hypothesis is that the researcher's prediction is not true. The alternative hypothesis is that the researcher's predicted difference is true.
2023-06-25 07:12:22

Amelia Sanchez

QuesHub.com delivers expert answers and knowledge to you.
In sum, the two-sample (independent samples) t-test is a choice between two possibilities; a null hypothesis and an alternative hypothesis. The null hypothesis is that the researcher's prediction is not true. The alternative hypothesis is that the researcher's predicted difference is true.
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