Hypothesis testing: what, how and why [+ 5 learning resources] (2023)

Hypothesis testing is a method used by many analysts in the private and government sectors to make probable statements or assumptions about population data.

If you have ever been interested in or studied population data, you must have come across this important hypothesis testing tool.

Many methods can be used to make assumptions, but not all provide greater accuracy.

And if you're not sure about your data but still want to use it, it could be risky for your business.

Hypothesis testing is a good strategy to achieve a higher level of precision. It was fundamental in the analysis of the population.

In this article, I will discuss what hypothesis testing is, how it works, its benefits, and its use cases.

So, without further ado, let's get started!

What is hypothesis testing?

Hypothesis testing is a method of statistical inference that analysts use to test whether available population data sufficiently support a particular hypothesis and to make assumptions based on it.

This method allows analysts to easily test a hypothesis and determine the accuracy of the assumption based on the available data.

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(Video) Intro to Hypothesis Testing in Statistics - Hypothesis Testing Statistics Problems & Examples

In simple terms, it is a testing process based on inferential statistics that allows you to make a judgment on population data based on the collected sample data.

In general, it is almost impossible for analysts to find properties or a specific parameter of the entire population. But through hypothesis testing, you can make an informed prediction and decision based on the sample data and its accuracy.

Types of hypothesis tests

The different types of hypothesis tests are:

  • Null Hypothesis:The statistics show that the sample data is robust and there is no correlation between the two variables in the provided sample data.
  • Alternative hypothesis:It proves the main hypothesis and contradicts the null hypothesis. It is the main driving force in the testing process, as it shows a correlation between two variables in the sample data.
  • Undirected hypothesis:This type of hypothesis testing serves as a two-sided hypothesis. Shows that there is no direction between two variables in the sample data and that the actual value does not match the predicted value.
  • directional hypothesis:The directional hypothesis shows some relationship between two variables. Here, one variable in the sample data can affect the other variables.
  • Statistical hypothesis:It helps analysts assess whether data and value meet a specific hypothesis. It is very useful for making statements and assumptions about the result of a parameter of a population sample.

Next, we will discuss methods for testing hypotheses.

Hypothesis testing methods

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As an analyst, in order to judge whether a given hypothesis is true or not, you need a lot of plausible evidence to draw a conclusion. In this testing process, a null and alternative hypothesis are established before the evaluation begins.

Hypothesis testing involves not just a single method, but many to assess whether the sample data is favourable. As an analyst, you must consider your data and sample size and choose which hypothesis testing method is right for you.

normality test

It is a standard method for testing hypotheses to analyze the regular distribution in sample data. During the testing process, the clustered data points are checked to see if they are above or below the mean.

In this statistical test, points are equally likely to fall above or below the mean. The result is a bell curve evenly distributed on both sides of the mean.


This is another type of hypothesis test that is used when population data is normally distributed. Tests whether the mean of two separate population parameters is different when you know the variance of the data.

When analyzing population data, you will most likely use this type when the sample size of the data is greater than 30. Also, the central limit theorem is another reason why the z test is appropriate, since the theorem states that the samples are normally distributed. as the sample size increases.

Test T-Test

t-test hypothesis tests are used when the sample size is limited and generally distributed. In general, it is mainly applied when the sample size is less than 30 and the standard deviation of the parameter is not known.

When you perform a t test, you use it to calculate confidence intervals for specific population data.

(Video) Hypothesis Testing - Introduction

chi-square test

The chi-square test is a popular hypothesis testing technique often used to assess the fit and completeness of a data distribution.

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However, the main reason for using this type of hypothesis is to test the population variance against a population variance with an assumed or known value. Various ChisquareTests are done, but the most common type is the chi-square test for variance and independence.

ANOVA tests

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Abbreviated as analysis of variance, it is a statistical test method that helps to compare two sets of sample data. However, you can compare more than two averages at the same time.

It also declares a dependent variable and an independent variable for sample data. Using ANOVA is quite similar to using the z test and the t test, but the latter two are limited to only two means.

How does hypothesis testing work?

Any analyst using hypothesis testing uses sample data for analysis and measurement. During the test, the sample data is used to test the null and alternative hypotheses.

As we have already discussed, the null hypothesis and the alternative hypothesis are completely mutually exclusive, and only one of them can be true during the test result.

However, there are some cases where the null hypothesis is rejected; The alternative hypothesis is not always true.

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p-value:As the testing process begins, the p-value or probability value is involved and indicates whether or not the result is significant. In addition, the p-value also shows the probability of finding an error in rejecting or failing to reject a null hypothesis during the test. The resulting p-value is either 0 or 1, which is then compared to the significance level or alpha level.

Here, the significance level defines the acceptable risk of rejecting a null hypothesis during testing. It is important to remember that the result of the hypothesis test can give rise to two types of errors:

  • type 1 erroroccurs when the test result rejects the null hypothesis even though it is true.
  • type 2 errorappears when the null hypothesis is accepted by the sample result, even if it is false.

All values ​​that lead to the rejection of the null hypothesis are stored in the critical area. And it is the critical value that separates the critical regions from the others.

Steps to perform the hypothesis test

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Hypothesis testing involves four main steps:

  • Define hypothesis:In the first step, your task as an analyst is to define the two hypotheses so that only one is true. The null hypothesis indicates that there is no difference in mean BMI, while the alternative hypothesis indicates that there is a significant difference in mean BMI.
  • The plan:The next step is to design an analysis plan for how to analyze the sample data. It is important that you sample and collect sample data to ensure that your hypothesis is tested.
  • Analyze sample data:Now that you've decided how to analyze the data, it's time to begin the process. You must physically analyze the sample data to avoid redundancy. When analyzing the data, you should verify that the samples are independent of each other and that both sample sizes are large enough.
  • Calculate test statistic:At this stage, you need to calculate the test statistics and find the p-value. The p-value is determined assuming that the null hypothesis is true.
  • Evaluate the result:In the last step, you need to evaluate the result of the hypothesis test. Here you decide whether to reject the null hypothesis or give a plausible explanation based on the sample data.

Now let's explore the benefits of hypothesis testing.

Advantages of Hypothesis Testing

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The advantages of hypothesis testing are:

(Video) Hypothesis testing

  • Helps you analyze the strength of your claim for a data decision.
  • As an analyst, you can use it to create a trusted environment for making decisions on sample data.
  • This allows you to determine if the sample data used in the hypothesis test is statistically significant.
  • It is beneficial to assess the reliability and validity of test results in any systematic testing process.

Helps extrapolate data from one sampling stage to a larger population as needed.

Using hypothesis test cases

Hypothesis testing is used in all industries to correctly guess the accuracy of sample data. Some real world examples of hypothesis testing are:

#1.clinical trials

Hypothesis testing is widely used in clinical trials because it helps medical professionals decide whether or not a new drug, treatment, or procedure is effective based on sample data.

A doctor may think that treatment may lower potassium levels in some patients. Doctors can measure potassium levels in a group of patients before treatment and check the levels again.

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Then the doctor performs hypothesis tests, where H0: Unafter = Ubefore, that is, the potassium level after applying the treatment will be the same as before. Another hypothesis raises Ha: After < Ubefore, which means that potassium levels decreased after the application of the treatment.

Therefore, if the p-value is below the significance level, the doctor can conclude that the treatment may lower potassium levels.


Hypothesis testing is used in manufacturing facilities to help supervisors decide whether or not the new method or technique is effective.

For example, some manufacturing facilities may use hypothesis testing to see if the new method will help them reduce the number of defective products per lot. Assume that the number of defective products is 300 per lot.

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The manufacturer shall average the total number of defective products produced before and after applying the process. You can do hypothesis tests and use hypotheses H0: Unafter = Ubefore, where the average number of defective products produced after applying a new method is the same as before.

Another hypothesis shows that HA:Unafter is not equal to Ubefore, which means that the total number of defective products produced after applying the new method is not equal.

If the p-value after the test is less than the significance level, the manufacturing unit can conclude that the number of defective products produced has changed.


Hypothesis testing is often used to find out if fertilizers or pesticides cause plant growth and immunity. Biologists can use the tests to show that a given plant can grow more than 15 inches after applying the new fertilizer.

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The biologist can apply the fertilizer for a month to collect sample data. When the biologist runs a test, one assumption is H0 U = 15 inches, which suggests that the fertilizer does not improve average plant growth.

(Video) Statistical Tests: Choosing which statistical test to use

Another hypothesis shows HA:U>15 inches, suggesting that fertilizers cause an improvement in average plant growth. After testing when the p-value is less than the significance level, the biologist can now show that the fertilizers produce more growth than before.

learning aids

#1.Statistics: A Step-by-Step Guide from Udemy

Hypothesis testing: what, how and why [+ 5 learning resources] (11)

Udemy offers acourse statisticsin which you will learn a step-by-step introduction to the statistics that cover hypothesis testing. This course includes examples and lessons from a former Google data scientist to help you master confidence intervals, hypothesis testing, and more.

#2.Basic Statistics for Udemy Data Analysis

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this udemyBasic statistics course for data analysisIt will help you learn statistics with real projects, fun activities, hypothesis testing, probability distributions, regression analysis, and much more.

#3.Statistics for data science and business analytics

Hypothesis testing: what, how and why [+ 5 learning resources] (13)

OStatistics course for data science and business analysisis offered by Udemy to help you learn to test hypotheses. It covers various statistical topics and enables data scientists and business analysts to learn and master them. Includes inferential and descriptive statistics and regression analysis.

#4.Hypothesis Test by Jim Frost

This book is available atamazonasand is an intuitive guide to help analysts make data-driven decisions.

to seeproductsAssessmentPreis
Hypothesis testing: what, how and why [+ 5 learning resources] (14)Hypothesis Testing: An Intuitive Guide to Data-Driven DecisionsNo reviews yet23,74 $ buy on amazon

It covers how hypothesis testing works, why you need it, how to use confidence intervals, p-values, significance levels, and many other topics effectively.

#5.Scott Hartshorn Hypothesis Test

This book is unique with its visual examples and is best suited for beginners who want a quick guide to testing hypotheses.

It will introduce you to the meaning of stats, the types, and how they work. It doesn't require in-depth knowledge of statistics, but it explains everything intuitively.

Last word

Hypothesis testing helps verify an assumption and then develops statistical data based on the evaluation. It is used in many industries, from manufacturing and agriculture to clinical trials and IT. This method is not only accurate, but also helps you make data-driven decisions for your business.

So look at thoseLearning resources to become a business analyst.


1. Hypothesis Tests: Difference In Means: Educational Materials
(David Flenner)
2. Hypothesis testing. Null vs alternative
(365 Data Science)
3. Computer Scientist Explains One Concept in 5 Levels of Difficulty | WIRED
4. t test statistics(t test)(standard deviation)(student t test)(average mean)
(Research Methodology Advanced Tools)
5. Choosing which statistical test to use: Practice examples
(Dr Nic's Maths and Stats)
6. Scientific Method for Kids | Learn all about the Scientific Method Steps
(Learn Bright)
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