Whats the formula for variance between batches?

In summary, the conversation is about a lab for a Civil Engineering Materials class where the person is looking for the "between batch variation" for different cylinders of Portland cement concrete. Despite searching in their book, notes, and online, they were unable to find the information. A link to a digital book discussing batch variations is provided, which mentions S as the compressive strength in MPa and suggests that the variation may simply be the absolute value of the difference between the compressive strength of both batches. The person also mentions that they are not a civil engineer and may not fully understand the topic.
  • #1
Fat Ryan
50
0
Im working on a lab for my Civil Engineering Materials class and its asking for the "between batch variation" (SBB^2) for different cylinders of Portland cement concrete. Its not written anywhere on the lab sheet. And I've looked in my book, notes, and Google. I am getting nothing here :/
 
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  • #2
any1?
 
  • #3
keep in mind I am not studying to be a civil but mech engineer so this is the best i can come up with.

heres a link to a digital book that discusses batch variations:
http://books.google.com/books?id=g8...age&q=cement between batch variation&f=false"

if you look at table 1.7 and read the page above it it seems as if S=compressive strength in MPa. so you are looking at the difference between compressive strength of both batches.
absolute value of S(batch A)-S(batch B).
maybe your making it harder than it seems when it might just be a trivial subtraction operation. and maybe that is why you can't find a formula to it because its that simple.
anyways keep in mind this is not my specialty and i know absolutely nothing about civil but this is what i understood purely from the text.
 
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  • #4
If you really expect help within 35 minutes of posting your question, you're in the wrong place.
 
  • #5
hhn, thanks for the help. i ended up getting help from another grad student before i could even get back to my computer though. thanks for your time though.
 
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1. What is variance and why is it important to calculate between batches?

Variance is a measure of how spread out a set of data points are from the mean. It is important to calculate between batches because it allows scientists to determine the consistency or variability of results between different groups or batches. This helps to ensure the reliability and reproducibility of experiments and can aid in identifying any potential issues or trends.

2. How is the formula for variance between batches calculated?

The formula for variance between batches is calculated by taking the sum of squared differences between each data point and the mean of the entire set, divided by the number of data points. This can also be expressed as the sum of squared differences between each data point and the mean of the batch, multiplied by the number of data points in the batch, divided by the total number of data points.

3. Can the formula for variance between batches be applied to any type of data?

Yes, the formula for variance between batches can be applied to any type of numerical data, including continuous, discrete, or categorical data. However, it is important to note that the interpretation and use of variance may differ depending on the type of data being analyzed.

4. How can the results of the variance between batches be interpreted?

The results of the variance between batches can be interpreted as a measure of the variability or spread of data points within each batch. A larger variance indicates a greater amount of variability, while a smaller variance indicates a more consistent set of data. Additionally, the variance can be compared between different batches to determine if there are any significant differences or patterns.

5. Are there any limitations to using variance between batches as a measure of variability?

While variance between batches is a useful measure of variability, it does have some limitations. For example, it does not take into account the direction of differences between data points, and it can be heavily influenced by extreme values or outliers. It is important to consider these limitations and to also use other measures of variability, such as standard deviation, in conjunction with variance to get a more complete understanding of the data.

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