What-is-ANOVA-in-Statistics_

Complete Details on What is ANOVA in Statistics?

What is ANOVA in statistics? Should I prefer Anova over the t-test? These are some of the questions that a statistics student should know. If you do not have any idea regarding these questions, do not worry; you are at the right place.

If I simply say ANOVA (Analysis of Variance) is used to test the hypothesis equality of three or more values of the population. Apart from this, it can be used in various ways like one-way, two-way, and N-way. Below, I have mentioned and covered all the useful information about What is ANOVA. So, without wasting more time, let’s move to the details. 

What is ANOVA and why is it used?

It is a type of analytical tool used for statistical data. It divides an observed value within the data set into two different parts: systematic and random factors. 

The systematic factors are used to represent the statistical influence on the provided data sets, whereas the random factors do not have any statistical influence on the data. 

Various analysts use ANOVA to determine the statistical influence, showing the effect of independent variables on the dependent variables for the regression period. Now, you have an idea about what is ANOVA, so let’s know why it is used? Or should I prefer Anova over the t-test?

You can use ANOVA for analyzing the comparative experiments. These comparative experiments must have a significant difference in the outcomes of the experiments. Here, the significance statistics are determined by calculating the ratio of two variances.

Key point:
What is the principle of ANOVA?
The basic principle of ANOVA: It is used for testing the difference between the populations’ mean. It is calculated by analyzing the amount of variation in the samples. 

Take a look at the history of ANOVA!!

The z-test and T-test methods were implemented in the 20th century and were used until 1918 for statistical analysis. Initially, ANOVA is known as the Fisher analysis of variance as Ronald Fisher creates it; this has the extension of z-test and t-test. 

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The terminology ANOVA was renowned in the year 1925 when it was written in Fisher’s book known as “statistical methods for research workers.” Initially, it was included in experimental psychology, but later, it was expanded to more complicated subjects.

What is the formula for ANOVA?

F = (MST/MSE)

Where,

F = ANOVA Coefficient.

MST = Mean sum of squares due to treatment.

MSE = Mean sum of squares due to error.

Besides statistics, is ANOVA functional in other applications?

Yes, it is!!

Even though it has been seen that the ANOVA includes complicated statistical steps, it can also be beneficial for various businesses.  

Various organizations are using ANOVA for making better business decisions. ANOVA helps them make alternative products for their customers. This helps consumers to have a number of choices.

Apart from this, ANOVA is used for

  • Comparing the production of different varieties of wheat under different fertilizing brands.
  • Comparing and analyzing the effectiveness of several advertisements on social media. These advertisements are related to sales of the products.
  • Analyzing and comparing the different lubricants in various kinds of vehicles.

How to use ANOVA?

When one has the knowledge of what is ANOVA, then one can easily use ANOVA for various purposes that also depend on the design of the research. Usually, there are three different ways to use ANOVA that are one-way, two-way, and N-way ANOVA. Let’s get the details of each of them.

One-Way ANOVA

It has one independent variable. 

Let’s take an example of it- if a nation wants to evaluate the IQ difference, then it can have 2,20, even more categories to compare the values. 

Two-Way ANOVA

The two-way ANOVA is also known as factorial ANOVA, which is used for two independent variables. 

Let’s take an example of it; the two-way ANOVA is used to examine the difference between IQ scores by gender (independent variable 2) and country (independent variable 1). 

Moreover, this two-way ANOVA is used to check the interaction in the two independent variables. 

For example, females might have a higher IQ score than males, but the difference might vary as greater or less for the European countries compared to other North American countries.

N-Way ANOVA

When a researcher uses more than two variables, or we can say that if the research is done with n as the number of independent variables, it is termed N-Way ANOVA. 

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An example of it is the potential difference in IQ scores that can be tested by Gender, Ethnicity, Country, Age group, and much more simultaneously. 

Key point:
When should I go with ANOVA?
It is always beneficial if you use ANOVA as the marketer. In short, it is used when you need to test a specific hypothesis. 
With the help of ANOVA, you can easily understand the response of the different groups with the null hypothesis. 
Here, the null hypothesis means that the groups have equal means (average). In case you find a statistically significant result, it implies that the tested groups of the population are different (or unequal). 
In this condition, ANOVA can help you determine the means of the population easily. 

What is the purpose of ANOVA?

In simple words: For omnibus ANOVA test

There is no major difference between the groups for the null hypothesis value. The other hypothesis supposes that there must be one particular difference between the groups. 

The researcher can test the estimated value of ANOVA that is generated after cleaning the data. Then they measure the F-ratio and the p-value, which is the associated probability value. 

If the associated p-value is 0.5 smaller than the F, then the value of the null hypothesis can be rejected; therefore, one can conclude that the mean value of a group is not equal. To check the differences of the group, the researcher uses the Post-hoc testing method.

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What if one finds statistical significance? 

When you use an ANOVA test, one is trying to determine the significant difference of the statistical data among the groups. If one successfully finds the differences, you are required to analyze where the group’s differences lay.  

This is the correct place where you can use Post-hoc tests that use t-tests methods to check the mean difference in the groups. There are various additional tests used to control the type I error rate, including the Scheffe, Tukey, Bonferroni, and Dunnet test.

What are the assumptions and data levels?

Besides the understanding of what is ANOVA, the level of calculation of the assumptions and variables of the test plays an essential role in ANOVA. 

For the testing of ANOVA, the dependent variables should be continuous (ratio or interval) level of measurement. In ANOVA, the independent variables should be categorical (ordinal or nominal) variables. 

Just as a t-test, it is used for some assumptions and a parametric test. It is also used to distribute the data normally and also used as homogeneity of variance, which means the variance must be equal among the groups. 

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ANOVA also has the observed value that is independent of each other. To make sure, researchers are planning to study out the confounding or extraneous variables. It has various ways to control confounding variables.  

How to consider the testing of the assumptions?

Key points

  1. The population must be a normal distribution for the drawn samples.
  2. In the case of independent variables: the model cases must be independent of each other.
  3. Homogeneity of variance: here, homogeneity means that the variance of a group setting must be equal.

The assumptions are tested using statistical software (such as Intellectus Statistics). Moreover, the homogeneity of variance’s assumption is tested using a test like the Brown-Forsythe or Levene test. 

On the other hand, the normality distribution of the scores is tested using the values of kurtosis and skewness, histograms, or using a test like Kolmogorov-Smirnov or Shapiro-Wilk. The assumption of independence is determined from the design of the study.

What if the assumptions are violated?

It is essential to notice that ANOVA is not used for violation of the assumed independence value. If you have to violate the assumed value of normality or homogeneity, one can easily get the test and trust the outcomes. 

If any of the independent assumptions are violated, then the output of ANOVA is considered invalid. But, with the homogeneity violations, the other analysis can be considered as robust for the equal-sized groups. If you have a large sample size, the violations of normality are considered to be ok.

A brain booster: Relative Analyses term: ANCOVA and MANOVA As per the requirement, the researchers have expanded the use of ANOVA in ANCOVA and MANOVA.ANCOVA stands for Analysis Of Covariance, which is used if the researchers need to include one or more covariate variables values in the analysis. On the other hand, MANOVA is the term for the multivariate analysis of variance used for two or more dependent variable values.

Conclusion

This blog has all the details on what is ANOVA, its history, formula, ways to use ANOVA, and much more. We hope that this blog helps you to understand the meaning of ANOVA. One can easily use this to check the hypothesis value for the large population data. This can be used in three different ways, like a one-way test, a two-way test, and an n-way test, and all of them are used for different purposes. 

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Frequently Asked Questions

What is the difference between chi-square and Anova?

Chi-square is a nonparametric criterion used for comparing each characteristic of the population test. Whereas in ANOVA, the user easily analyzes the quantitative characteristic’s dependence on different qualitative characteristics.

What data is needed for Anova?

ANOVA considers that the data need to be normally distributed. Therefore, in ANOVA, it is necessary that the dependent variable should be a measurement’s continuous level. Apart from this, the independent variables should be categorical variables.

What is Anova simple explanation?

Analysis of variance is one of the statistical test techniques used for checking whether two or more groups’ means are significantly distinct from one another. ANOVA examines the influence of one or more parameters by comparing the various samples’ means.