Fitting Normal Distribution Histogram - Help Needed

In summary, the conversation discusses the use of a histogram to fit a Gauss shape to a set of data. The speaker initially tries to use the regular equation for a normal distribution but finds that it does not fit the data well. They then consider the possibility of a bimodal distribution or using a different type of graph, such as a boxplot. The conversation also mentions trying a skew normal distribution as a potential solution.
  • #1
randa177
91
1
I have a set of data that I used to create a histogram, and would like to fit it with a Gauss shape...I used the regular equation for a normal distribution, using the mean value and the standard deviation of my data, but the Gauss shape doesn't seem to be really fitting my data... I might be doing something wrong... I am attaching it here...

Thanks!
 

Attachments

  • Stat_Gauss.pdf
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  • #2
Yeah, the data doesn't look normal. Maybe it's a bimodal distribution of some sort?
 
  • #3
actually when I use the same of data on an online program I get better results...
These are the numbers I am using:
-2.1
-1.8
-1.6
-1.4
-1.2
-1.1
-1
-0.9
-0.8
-0.7
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.8

Do you know what the problem might be?
PS: Try putting these numbers here: http://azzalini.stat.unipd.it/SN/sn-fit.html
It gives a reasonable solution...

Why isn't giving me similar solution? Any idea?
 
  • #4
I agree with CrGreatHouse - your data shouldn't be considered to be normally distributed.

More importantly, if the data in your final post is your entire data set, the sample size is far too small to get a reliable idea of shape of the underlying distribution. A different type of graph (boxplot perhaps) would be a far better choice.
 
  • #5
What if I use a skew normal distribution... do you think that might fit the data better?
 

FAQ: Fitting Normal Distribution Histogram - Help Needed

What is a normal distribution histogram?

A normal distribution histogram is a graphical representation of a normal or Gaussian distribution, which is a type of probability distribution that is commonly found in nature. It is a bell-shaped curve that shows the frequency of data points that fall within a certain range of values.

How is a normal distribution histogram fitted?

A normal distribution histogram is fitted by adjusting the parameters of the normal distribution curve, such as the mean and standard deviation, to best match the shape and location of the data points in the histogram. This can be done manually or through statistical software.

Why is it important to fit a normal distribution histogram?

Fitting a normal distribution histogram is important because it allows us to understand the underlying distribution of the data and make inferences about the population from which the data was collected. It also helps us to identify any outliers or unusual data points that may affect our analysis.

What are some methods for fitting a normal distribution histogram?

Some methods for fitting a normal distribution histogram include the method of moments, maximum likelihood estimation, and least squares estimation. These methods involve using mathematical equations and statistical algorithms to find the best fit for the data.

Can a normal distribution histogram be used for any type of data?

No, a normal distribution histogram is most suitable for data that is normally distributed, meaning that the data is symmetrically distributed around the mean and follows a bell-shaped curve. If the data is not normally distributed, other types of histograms or data visualizations may be more appropriate.

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