# Search results

1. ### Compute prediction intervals in Random Forest Regression

What is the problem that you are trying to solve? Beyond prediction, that is. What is unique about this process that you wouldn't use SPC to control the process?
2. ### Design of experiments across the time

I'm not a SAS user, but if you are willing to share your data, I could look at it in Minitab.
3. ### Hello statisticians and data enthusiasts!

Welcome Cedric I too am a practitioner in industrial statistics, and am well versed in SPC and DOE. Not so much in sampling though I can get by if necessary. I am new to machine learning, but am accomplished in reliability, so I may be able to assist in applying that to your maintenance problems.
4. ### Question abou autocorrelation

It depends on the measure used in the times series. If you were tracking GDP, which is a measure of the performance of the economy, you would expect to see autocorrelation over shorter time periods. Whether you are in a boom or a depression/recession, consecutive measures of GDP would...
5. ### Generating info about a population from a sample

Are the apartments of differing sizes (e.g., 1, 2 or 3 bedrooms), or quality? Or are there different levels of repair (e.g., painting, plumbing, HVAC)? Any of these might explain the grouping.
6. ### Generating info about a population from a sample

It may be a little more complicated than that. A histogram of the data shows some gaps, and a probability (Q-Q) plot shows some dog leg bends that may indicate a mixture of 3 possible groups. See the attached graphs for this. If this is true, you will need to identify these groups and apply...
7. ### Correlation of two variables through others

I think you are out of luck. The variability between each 1000 piece sample is likely to be much greater than the variability within each sample. This would overshadow any potential correlation that you are seeking. If the material were relatively homogeneous (e.g., steel, aluminum, etc.)...
8. ### Correlation of two variables through others

Can you provide a little more context to your scenario? MOE = Modulus of Elasticity? What does frequency mean in this context? How were the samples collected? Are they all from the same batch of material? One group per batch? One/two piece(s) per batch?
9. ### Regression with error in the dependent var.

In Minitab, use Orthogonal regression. This is designed for error in both independent and dependent variables.
10. ### Unfortunately, Minitab 18 took their Help files to the cloud and do not provide the formulas as...

Unfortunately, Minitab 18 took their Help files to the cloud and do not provide the formulas as completely as before. However, notice that the SE are increasing as the number of At Risk decreases, so it is a sample size function.
11. ### Kaplan-Meier Survival Analysis - advice wanted

I use Minitab for reliability (survival) analysis. Because the data are left censored (no idea when the trees sprouted), right censored and interval censored (no idea when during a given year the tree died, I used a Turnbull estimate rather than Kaplan -Meier, but still duplicated your...
12. ### Statistical Validation of a Labelling Method

Are these categories nominal or ordinal in nature? If nominal try Fleiss' Kappa. If ordinal, use Kendall rank correlation coefficient. A minimum of 50 samples Pick a policy, then select samples that both pass the policy and fail the policy
13. ### Group has lower overall % despite winning each category of %'s

This is known as Simpson's Paradox.
14. ### How to deal with observations error in linear regression

I think they are referring to errors in variables regression. Specifically, error in the independent measure.
15. ### Vector Autoregressive Models

I thought I would throw this in from a course I teach in problem solving. There should be some overlap in statistics. Three rules of causality: A correlation or association exists between the hypothesized cause and the effect Cause must precede effect in time The mechanism linking cause to...
16. ### Histograms Reveal Potential Problem

Can you use nonparametric counterparts such as median, confidence interval for the median, quartiles, etc.?
17. ### Unusual distribution of the continuous outcome

It appears there are 4 major groupings. Would it make sense to perform a cluster analysis of the HCPCS codes into 4 clusters then treat these clusters as an indicator variable in your regression? Would the results be interpretable?
18. ### Unusual distribution of the continuous outcome

This looks more like a mixture of different groups, which should not be transformed, but further investigated.
19. ### Interpreting a hierarchical cluster analysis using dendrogram

Each clustering method has its own set of strengths, weaknesses, and tendencies. Wards method tends to form clusters with similar numbers in each cluster. This may or may not make sense in your particular situation. Regarding the number of clusters, this is a judgment call. You can visually...