# Having Trouble Understanding Chi Squared Stuff

• Poop-Loops
In summary, the speaker is working on an e/m lab and is struggling with understanding the notation and calculations. They mention trying to figure out which standard deviation to use and how to calculate degrees of freedom. They also joke about making up data to get grant money. They then ask for help understanding degrees of freedom and provide links to resources on chi-square tests.
Poop-Loops
So I have my fit for my data (in this case it's the e/m lab, where the slope of my trend line = e/m).

And I calculated the required y - (Ax + B) values, but I have no idea what to use for standard deviation to divide each value by. To be honest, I'm just lost in the notation. I remember in the lecture hearing that if all the STD's are the same, you can pull that out of the sum, but I have no idea which STD's he was talking about, since I have 3 different measured quantities.

Also, degrees of freedom. Since I used 5 data points and had to measure 3 different quantities for each point, I would use D = 5 - 3 = 2?

I figured it out! I just make up the data to make it look pretty! That's how you get all the grant money.

No, seriously, I could still use some help.

I think I figured out which STD to use. Since my y-values are averages from 5 sets of data to get 5 data points, I just use the STD for the 5 different sets of data as my 5 different STD's, right?

I'm still not sure I understand the degree's of freedom, though.

## 1. What is Chi Squared?

Chi Squared is a statistical test used to determine the relationship between two categorical variables. It measures how well the observed data fits with the expected data.

## 2. How do I interpret the results of a Chi Squared test?

The results of a Chi Squared test are typically shown as a p-value. A p-value less than 0.05 is considered statistically significant, meaning there is a relationship between the variables. A p-value greater than 0.05 indicates that there is no significant relationship between the variables.

## 3. What does it mean if the Chi Squared test gives a high value?

A high Chi Squared value indicates that the observed data significantly deviates from the expected data, which suggests a strong relationship between the variables being tested.

## 4. Can the Chi Squared test be used for continuous variables?

No, the Chi Squared test is specifically designed for categorical variables. For continuous variables, other tests such as the t-test or ANOVA should be used.

## 5. How is the Chi Squared test different from a t-test?

The Chi Squared test is used for categorical data, while the t-test is used for continuous data. Additionally, the Chi Squared test assesses the relationship between two variables, while the t-test compares the means of two groups.

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