# Search results

1. ### Experimental Design Help

Blocking is used to minimize the impact of a known or suspected source of variation that is not of interest in the experiment. All levels of the treatment should be equally represented (balanced) within each block. Experimental units should be randomly assigned to these treatment levels.
2. ### Testing variables for confounding

I'm coming at confounding from an experimental design perspective where confounding occurs as you fractionate factorial designs. Since the authors are distinguishing between confounding and multicollinearity, they may mean something different by that term such as confounding with a variable...
3. ### Testing variables for confounding

Run a correlation matrix on the levels of the independent variable. A correlation coefficient of 0 is ideal indicating an orthogonal relationship between variables. A correlation coefficient of 1 would indicate perfect confounding between the variables. Correlation coefficients in between...
4. ### Statistics for market analysis

I would phrase it differently: - Beta < 1: Events are occurring at a decreasing rate (Orders are decreasing) - Beta = 1: Events are occurring at a constant rate (Customers are putting there orders in randomly) - Beta > 1: Events are occurring at an increasing rate (Orders are increasing)
5. ### Statistics for market analysis

I have no disagreement on its flexibility outside reliability. The ability of the Weibull distribution to model such a wide variety of shapes is why it is so widely used. My real point was that there are also other distributions that may be used to model events in time (see attachment), so...
6. ### Statistics for market analysis

Q1: This is straight forward reliability/survival analysis for events in time. There are many distribution other than Weibull that may also be used as well as non parametric methods. Q2: You might try reliability growth modeling to predict the current year from prior years. Then plot the...
7. ### Help identi

With a multi-modal distribution, I would not conclude that either. It you could isolate the initial exposure and remove the secondary and tertiary exposures, it might be a symmetrical, bell-shaped distribution.
8. ### Help identi

It is a histogram, but it is multi-modal. Not knowing exactly what is included, I would speculate that the The leftmost pattern might be the initial group exposed to measles, and the clusters that become lower and more ragged looking as you progress to the right may be from secondary and...
9. ### Help identi

The quality of this image is too grainy to read the scales. Can you attach a better image?
10. ### Statistical test to assess the relationship between an independent and dependent variable of an experiment

It depends on the question you want to answer. Both the t-test and the 1-way ANOVA can answer whether there is a difference, but your original question was whether there is a relationship. To answer that question, start with a graphical plot. If there appears to be a relationship that is...
11. ### Continous (Ordinal) Outcome with Middle Group as Target

Sorry for the delayed response. I just returned from a 10-day cruise from Vancouver to Hawaii. In an industrial situation, I would treat the response as a continuous response with a specification of 11-20. This maximizes the information content available in the data. For example, 0 is...
12. ### One way ANOVA or two way ANOVA? + non-parametric equivalents

The 2-way ANOVA would be the appropriate parametric test. During the analysis, you can test the specific contrast in which you are interested and not test those that are not of interest. Don't worry about the distribution of the raw data. The distribution of the residuals is what is...
13. ### What P value level do you suggest for this study?

I practice in industrial statistics where there is no pressure to publish. When I see p-values in that region, I will target that factor for further investigation. As an outsider, observing the reproducibility and replication crisis, the biggest failing that I see is the rush to publish based...
14. ### 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?
15. ### 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.
16. ### 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.
17. ### 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...
18. ### 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.
19. ### 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...
20. ### 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.)...