Statistics: How to find mean of bins

In summary, the conversation discusses how to find the mean for binned data. The suggested method is to use the weighted mean formula, where the value of each bin is multiplied by the number of data points within that bin. The conversation also mentions using the average value of the data samples in each bin, but it is clarified that the midpoint of the bin should be used instead.
  • #1
Niles
1,866
0

Homework Statement


Hi

Say I have the following bin sizes, where the number in paranthesis is the amount of data points contained in the bin:

20-29 : (2)
30-39 : (7)
40-49 : (12)
50-59 : (14)

How would I go about and find the mean for this binned data? I know that I should use

[tex]
mean = \frac{1}{N}\sum\limits_j {n_j x_j },
[/tex]

where bin j corresponds to a value xj and contains nj elements. But in my case, what are the values of the bins?
 
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  • #2
You usually treat this as a weighted mean problem. Think this way: if you needed to select one value from inside each bin, what value (intuitively) would be the one to pick if you didn't want to over- or under-estimate typical values in the bin? That's the value you use for x.
 
  • #3
statdad said:
You usually treat this as a weighted mean problem. Think this way: if you needed to select one value from inside each bin, what value (intuitively) would be the one to pick if you didn't want to over- or under-estimate typical values in the bin? That's the value you use for x.

I would use the average value of the data samples in that particular bin. Would you also do that?
 
  • #4
Niles said:
I would use the average value of the data samples in that particular bin. Would you also do that?

No - you need to use a number that comes from the bins, not the collected data.
 
  • #5
Then the average of the bin-size, i.e. for 20-29 it is 24.5?
 
  • #6
Yes - it's called the midpoint of the bin.
 
  • #7
Thanks, it is kind of you to help me.

Best wishes,
Niles.
 

1. What is the definition of mean in statistics?

The mean, also known as the average, is a measure of central tendency that represents the sum of all values in a dataset divided by the number of values in the dataset. It is used to describe the typical or average value in a dataset.

2. How do you calculate the mean of bins in statistics?

To find the mean of bins in statistics, you need to first determine the midpoint of each bin by adding the lower and upper limits of the bin and dividing by 2. Then, multiply each midpoint by the frequency of that bin and add all the results together. Finally, divide the sum by the total number of values in the dataset.

3. Can the mean of bins be used to represent the entire dataset?

No, the mean of bins is only an approximation of the true mean of the dataset. It is a useful tool for summarizing data and understanding its distribution, but it may not accurately represent the entire dataset.

4. How is the mean of bins affected by outliers?

The mean of bins is sensitive to outliers, as they can significantly affect the overall average. Outliers are extreme values that differ significantly from the rest of the data, and they can skew the mean towards their direction. It is important to identify and handle outliers carefully when calculating the mean of bins.

5. What are the advantages of using the mean of bins over other measures of central tendency?

The mean of bins provides a more detailed understanding of the distribution of the data compared to other measures of central tendency, such as the median or mode. It also takes into account the frequency of each value, providing a more accurate representation of the dataset. Additionally, the mean of bins can be easily calculated and interpreted, making it a popular choice in statistics.

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