quality

  1. B

    Control Chart - Which one to use - IMR or CUSUM

    Hi, I have a thesis study about statistical quality control. I have data from a chemical factory manufacturing powder paint. They want to use control charts to check particle size distribution. Data is not micron but percentage of the particles. For example sample 1 is 3.456 and it means...
  2. C

    Changing a target value that minimize the product being outside the specifications in

    I was doing problems in the article here. http://elearning.vtu.ac.in/10/enotes/06IPIM65/Mod10-NVN.pdf In the question on page 16 I don't understand part b) how to find a target value that minimize the product being outside the specifications. Can someone please explain to...
  3. C

    Changing process average in control charts

    Data is given for a X bar and R chart of subgroup size=4. . The control limits are for X bar chart: center line=178.46 UCL=184.1146 LCL=172.8054 for R chart: center line=8.3888 UCL=17.734 LCL=0 In this question I don't understand to do the following part : . Can...
  4. J

    Quality of regression

    Hey, i made a linear regression between two datasets of the form y=mx+b. I calculated m and b with a formula that is typical for this data. But it's not the least square method. I am trying to find a way to determine the quality of this m and b. Something like the correlation coefficient but...
  5. Y

    Multivariate Hotelling's T or univariate test?

    Hi, I am new to the board and tried to search for Hotelling's T but could not find an answer to my problem (the appropriate test statistic). I'm not sure if Hotelling's is the correct stat, or if one exists. Setup: I have two samples of different sizes, A and B, drawn from different...
  6. S

    Normality Assumption

    Say there is 100 observations, but these observations are equally broken into 2 genders and 5 cities. When creating a qq plot or just checking normality by the S-W statistic, can the 100 observations be tested all at once or does the data need to be broken out by genders or even the five cities?