A Reliable Tool For Chi Square Test Online
One of the best statistical tests that you can perform when you want to discover how likely it is to have the observed data fit what you expect is the chi square test online. After all, the chi square test online is simple and effective and allows you to analyze categorical data (data that can be divided into categories).
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One of the things that you need to understand about the chi square test online is that it isn’t suited to work with continuous data or percentages.
The Chi Square Test And The Null Hypothesis
One of the things that you need to know when you are making a chi square test is that the null hypothesis always assumes that the variables are independent which is the same as saying that the observed data doesn’t fit the model.
Chi Square Formula And Its Application
In order to make a chi square test, you need to use its formula. The truth is that it is a fairly simple and intuitive formula:
As you can see, you shouldn’t have any problems using it. However, when you have a lot of data, this process can be very tedious. So, we decided to show you a simple example with only a small set of data so that you can easily understand what you need to do to calculate the chi square value.
Let’s say that we want to know more about the relationship between the party affiliations and how they are distributed between males and females.
So, just take into consideration:
The Observed Data
| Democrat | Republican | Total | |
|---|---|---|---|
| Male | 20 | 30 | 50 |
| Female | 30 | 20 | 50 |
| Total | 50 | 50 | 100 |
The Expected Data
| Democrat | Republican | Total | |
|---|---|---|---|
| Male | 25 | 25 | 50 |
| Female | 25 | 25 | 50 |
| Total | 50 | 50 | 100 |
So, by using the formula we displayed above, you just need to replace the data that we have on the tables for the respective variables.
X^2 = ((20-25)^2/25) + ((30-25)^2/25) + ((30-25)^2/25) + ((20-25)^2/25)
X^2 = (25/25) + (25/25) + (25/25) + (25/25)
X^2 = 1 + 1 + 1 + 1 = 4
Confirm your results with our chi square value calculator.
So, you just discovered that the chi square is 4. But what does this mean? What can you conclude?
The truth is that simply looking at the chi square value you can’t conclude much. This is why you need to use the chi square test online which will help you achieve a much more interesting value – the p-value.
In order to calculate the p-value, you need to know the chi square value but you also need to know the degrees of freedom.
The Degrees Of Freedom
Usually denoted as d or df, the degrees of freedom are able to tell you how many numbers in your table are independent. The degrees of freedom are very important when you are performing a chi square test. After all, they factor the probability of independence into your calculations.
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So, after you have the chi square value, you need to take a look at the chart. The degrees of freedom will be expressed on the left. All you need to do is to check the row that has the closest number to the chi square value you got, and then just see the respective number located in the top row. This will give you the “Significance Level” or approximate probability for that value.
Returning to our example, we got a chi square value and a degree of freedom of 1. So, by looking at the table, we can see that we have a p-value of 0.0455. This value means that there is a 4.6% probability of the null hypothesis to be correct.