Methods for correlation and error analysis (statistical)

In summary, the conversation discusses a system of 7 objects with one measurement each and how they compare to two theoretical models. The machine used to take the measurements has a small error, so the data gathered has no significant error. The data does not fit a normal curve and attempts at using statistical tests have not yielded meaningful results. The need to reevaluate the models and measurements is emphasized.
  • #1
rodder58
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1. A system of 7 objects each have one measurement taken of them. These measurements are to be compared with two theoretical models, which theoretical model does the data fit best?[br]The machine used to measure the values has an extremely small error, so the data gathered does not have significant any error in the numbers I am interested in ( hence no standard deviation ). All numbers measured depend on each other. There are no multiple measurements done on the objects as error in machine is so small, thus no giant spread of data.



2. Example: => Experimental data : Object 1 (OJ1): 93.8, OJ2: 81.3, OJ3: 72.7, OJ4: 38.9, OJ5: 62.9, OJ6: 76.0 OJ7: 43.6 [br]
Theoretical Model 1: OJ1: 107.97, OJ2: 116.85, OJ3: 127.52, OJ4: 160.40, OJ5:132.10, OJ6: 121.03, OJ7: 155.14[br]
Theoretical Model 2: OJ1: 110.03, OJ2: 116.86, OJ3: 128.20, OJ4: 156.72, OJ5: 135.37, OJ6: 125.24, OJ7:153.99[br]




3. The data does not fit a normal curve, thus the Chi-squared method does not apply to it. It does not fit any other form of curve. A modified matched-pair analysis was attempted, but the lack of a standard deviation did not lead to a true meaningful answer. I have searched for a method, but to not avail. The Kolmogorov-Smirnov test was suggested, but I don't know if it can be applied to this system?
 
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  • #2
Please don't write your entire post in bold. It makes it hard to read.

See how much better this looks?

If the measurement errors are indeed "very small" (presumably on the order of 1/10, given the numbers you posted), both models are bad. Make that incredibly, incredibly bad.

You need to do something completely different here. Check your models (did you do the math right?), check your measurements (did you perform the procedure properly?), check everything. No statistical hypothesis test applied to observations and models this far in disagreement will have any validity whatsoever.

Edited to add:
You didn't say anything about the model uncertainties. If these differ between the two models then you can say one model is better than the other. I assumed small model uncertainties because of the precision you used in specifying the model values. If the uncertainty in some value is 40 for example, it is silly (at best) to say the expected value is 156.72.
 
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What is correlation analysis and why is it important?

Correlation analysis is a statistical method used to measure the strength and direction of the relationship between two or more variables. It is important because it allows us to understand the degree to which two variables are related, and can help us make predictions or identify patterns in data.

What is the difference between correlation and causation?

Correlation refers to a relationship between two variables, while causation refers to a situation where one variable directly affects the other. Correlation does not necessarily imply causation, as there may be other factors at play that are responsible for the observed relationship between two variables.

How do you calculate correlation coefficients?

There are several methods for calculating correlation coefficients, but the most commonly used is Pearson's correlation coefficient, which measures the linear relationship between two continuous variables. Other methods include Spearman's rank correlation coefficient, which measures the relationship between two ranked variables, and Kendall's tau coefficient, which measures the relationship between two ordinal variables.

What is error analysis and why is it important?

Error analysis is a method used to evaluate the accuracy of measurements or data. It involves identifying and quantifying sources of error in a study or experiment. It is important because it allows us to understand the limitations and potential biases in our data, which can help improve the validity and reliability of our results.

What are some common sources of error in statistical analysis?

There are several sources of error that can affect statistical analysis, including measurement error, sampling error, human error, and bias. Measurement error refers to inaccuracies in the measurement process, while sampling error refers to differences between the sample and the population being studied. Human error can occur during data collection or analysis, and bias can occur when there is a systematic deviation from the true value in the data.

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