All research starts with a problem that needs to be solved. From this problem, hypotheses are developed to provide the researcher with a clear statement of the problem.
To understand alternative hypotheses also known as alternate hypotheses, you must first understand what the hypothesis is.
When you hear the word hypothesis it means the accurate explanations in relation to a set of facts that can be analyzed when studied, using some specific method of research.
There are primarily two types of hypothesis which are null hypothesis and alternative hypothesis.
When you think about the word “null” what should come to mind is something that can not change, what you expect is what you get, unlike alternate hypotheses which can change.
Now, the research problems or questions which could be in the form of null hypothesis or alternative hypothesis are expressed as the relationship that exists between two or more variables. The process for this states that the questions should be what expresses the relationship between two variables that can be measured.
Both null hypotheses and alternative hypotheses are used by statisticians and researchers to conduct research in various industries or fields such as mathematics, psychology, science, medicine, and technology.
We are going to discuss alternative hypotheses and null hypotheses in this post and how they work in research.
Alternative hypothesis simply put is another viable option to the null hypothesis. It means looking for a substantial change or option that can allow you to reject the null hypothesis.
It is an opposing theory to a null hypothesis.
If you develop a null hypothesis, you make an informed guess on whether a thing is true or whether there is a relationship between that thing and another variable. An alternate hypothesis will always take an opposite stand against a null hypothesis. So if according to a null hypothesis something is correct to an alternate hypothesis that same thing will be incorrect.
For example, let's assume that you develop a null hypothesis that states "I"m going to be $500 richer" the alternate hypothesis will be "I'm going to get $500 or be richer"
When you are trying to disprove a null hypothesis, that is when you test an alternate hypothesis. If there is enough data to back up the alternative hypothesis then you can dispose of the null hypothesis.
The null hypothesis is best explained as the statement showing that no relationship exists between two variables that are being considered or that two groups are not related. As we have earlier established, a hypothesis is an assumed statement that has not been proven with sufficient data that could serve as a piece of evidence.
The null hypothesis is now the statement that a researcher or an investigator wants to disprove. The null hypothesis is capable of being tested, being verifiable, and also capable of being rejected.
For example, if you want to conduct a study that will compare the relationship between project A and project B if the study is based on the assumption that both projects are of equal standard, the assumption is referred to as the null hypothesis.
This is because the null hypothesis should be specific at all times.
For the curious: Sampling Bias: Definition, Types + [Examples]
Here are the purposes of the null hypothesis in an experiment or study:
Now, these are the principles of the null hypothesis:
1. The primary principle of the null hypothesis is to prove that the assumed statement is true. This is done by collecting data and analyzing in the study, what chance the collected data has in the random sample.
2. If the collected data does not meet the expectation of the null hypothesis, it is determined that the data lacks sufficient evidence to back up the null hypothesis therefore the null hypothesis statement is rejected.
Just as in the case of the alternative hypothesis the collected data in a null hypothesis is analyzed using some statistical tools that are made to measure the extent to which data left the null hypothesis.
The process will determine whether the data that left the null hypothesis is larger than a set value. If the data collected from the random sample is enough to serve as evidence to prove the null hypothesis then the null hypothesis will be accepted as true. And also defined that it has no relationship with other variables.
There are four types of alternative hypotheses, and we will briefly discuss them below.
We are going to look at the differences between the alternate hypothesis and the null hypothesis based on these six factors which are:
Null hypothesis is followed by an ‘equals to’ (=) sign. While the Alternative hypothesis is followed by these three signs;
In the null hypothesis, it is believed that the results that are observed are as a result of chance. While In the alternative hypothesis, it is believed that the observed results are the outcome of some real causes.
The result of the null hypothesis always shows that there have been no changes in statements or opinions. While the result of the alternative hypothesis shows that there have been significant changes in statements and opinions.
If the p-value in a null hypothesis is greater than the significance level, then the null hypothesis is accepted.
If the p-value in an alternate hypothesis is smaller than the significance level, then the alternative hypothesis is accepted.
The null hypothesis accepts true existing theories and also if there has been consistency in multiple experiments of similar hypotheses.
The alternative hypothesis establishes whether a relationship exists between two variables, and the result will then lead to new improved theories.
A researcher assumes that a bridge’s bearing capacity is over 10 tons, the researcher will then develop an hypothesis to support this study. The hypothesis will be:
For the null hypothesis H0: µ= 10 tons
For the alternate hypothesis Ha: µ>10 tons
In another study being conducted, the researcher wants to find out whether there is a noticeable difference or change in a patient’s heart arrest medicine and the patient’s heart condition.
For the alternate hypothesis: The hypothesis is that there might indeed be a relationship between the new medicine and the frequency or chances of heart arrest in a patient.
The hypothesis from example 2 in the alternate hypothesis implies that the use of one specific medicine can reduce the frequency and chances of heart arrest.
For the null hypothesis: The hypothesis will be that the use of that particular medicine cannot reduce the chance and frequency of heart arrest in a patient.
An alternate hypothesis states that the random exam scores are collected from both men and women. But are the scores of the two groups (men and women) the same or are they different?
For the null hypothesis: The hypothesis will state that the calculated mean of the men’s exam score is equal to the exam score of the women.
This is represented as
H0: µ1= µ2
H0= The null hypothesis
µ1= The calculated mean score of men
µ2= The calculated mean score of women
It is quite inappropriate to say or report that an alternate hypothesis was rejected. It is much better to use the phrase “the alternate hypothesis was rather not supported”.
The reason behind this use of words is that only the null hypothesis is designed to be rejected in a study. The alternative hypothesis is designed to prove the null hypothesis incorrect, to introduce new facts that can disprove the null hypothesis but it is not designed to be rejected.
It can either be accepted or not supported.
A researcher can use this formula to identify the alternate hypothesis in a study or experiment.
H0 and Ha are in contrast.
Therefore, if Ho has:
Equal to (=)
Greater than or equal to (≥)
Less than or equal to (≤)
And then Ha has:
Not equal (≠)
Greater than (>) or less than (<)
Less than (<) greater than (>)
If in a study, α ≤ p-value, then the researcher should not reject H0.
If in a study, α > p-value, then the researcher should reject H0.
α is preconceived. The value of α is determined even before the hypothesis test is conducted. While the p-value is derived from the calculation in the data.
The study a researcher wants to conduct will determine what hypothesis should be developed. However, the researcher should keep in mind what the purpose of the null and alternative two hypotheses are while developing the study hypothesis. So while the null hypothesis will accept existing theories that it found to be true or correct, and measure the consistency of multiple experiments, alternative hypotheses will find the relationship that exists (if any) between two phenomena and may lead to the development of a new and improved theory.
In this article, it has been clearly defined the relationship that exists between the null hypothesis and the alternative hypothesis. While the null hypothesis is always an assumption that needs to be proven with evidence for it to be accepted, the alternative hypothesis puts in all the effort to make sure the null hypothesis is disproved.
Researchers should note that for every null hypothesis, one or more alternate hypotheses can be developed.
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