Recent content by Miner

  1. Miner

    Help writing hypotheses!

    The null hypothesis is typically the status quo (e.g., the treatment has no effect, there is no difference/correlation, the coefficient is zero, etc.), while the alternate hypothesis is the opposite (e.g., the treatment does have an effect, there is a difference/correlation, the coefficient is...
  2. Miner

    Hierarchical clustering? Ward's linkage? K-mean clustering? anova?

    I did some research on linkage and distance methods in the past. The attached is a distilled summary of that. Regarding the sample sizes. Reliability will depend on the separation between clusters. If they are widely separated, a relatively small sample will suffice. As the separation...
  3. Miner

    Income Inequality Data

    Is this what you are looking for?
  4. Miner

    What model to estimate the prices of used cars?

    There will also be a discontinuity in the regression caused by the supply chain disruption in electronic chips used in new cars. The price of used cars skyrocketed when new cars could not be built.
  5. Miner

    wheres my cat?

    As soon as I read fed2's post I was waiting for this shoe to drop.
  6. Miner

    The most appropriate method in this case

    Why? Your stated goal was to determine the cause of death for machines that have live more than 1500 days. Regression of any type will not provide this information. Always include all of your available data when performing a reliability analysis. Excluding the data less than 1500 days will...
  7. Miner

    The most appropriate method in this case

    I think using Cox regression is an overkill solution. Your stated goal was to determine the cause of death for machines that have live more than 1500 days. A simple Pareto chart of the 900 will provide this information. The one surviving machine will not change your conclusions. Just because...
  8. Miner

    F test significant but simple contrasts not

    An ANOVA is an omnibus test. It does not actually test all possible contrasts, but effectively tests the largest effect. You only know that one of the contrasts is significant. That is why you need Post Hoc tests to determine which contrast(s) are the cause.
  9. Miner

    F test significant but simple contrasts not

    Yes. Assuming t0 = 1, t1 = 2, ..., Brett is testing the logical contrasts. However, it is possible that the change over time was not linear, an unaccounted covariate affected the measurements for some time periods, etc. resulting in a different contrast having a larger impact.
  10. Miner

    F test significant but simple contrasts not

    That is one possibility. A second possibility is that there is another, stronger contrast that is driving the main effect.
  11. Miner

    One-way ANOVA and Two-sample T-test give different results for two groups

    The assumption for equal variances was also violated.
  12. Miner

    ?data analyst == statistician?

    In my company, there are a lot of data analyst titles that have nothing to do with statistics. They do analyze data, but more in the way an accountant would analyze debits and credits, profit and loss.
  13. Miner

    Hello Everyone-52 yr old and back in college and statistics is kicking my butt

    What is even worse is that different disciplines will use different words and different symbols to describe the same concept, so you need to learn multiple new languages. I work in industry and this is my everyday job. Industrial statistics is quite different from that taught in schools.
  14. Miner

    What is difference between Student's t test and Chow test?

    The t-test shown in the article focuses solely on detecting differences in the slopes. The Chow test looks at changes in the slope AND the y-intercept.
  15. Miner

    How to analyze UNPAIRED data for correlation/regression

    You cannot perform correlation or regression without paired data. The only thing that you can do with this type of data is to perform a 2-sample t-test (or equivalent) to determine whether there is a statistically significant difference in means. However, any significant differences will not...