applied statistics

  1. J

    Call Centre Strategy

    Hi, I'm working on a research project for a call centre, it's been a while since I have done any applied statistics so I could really use some help. Here's what I want to do: I need to understand why customers are calling into the call centre so I can design an appropriate queuing and...
  2. G

    Do I need to transform my data before PCA?

    Hi, I have 18 variables (soil biogeochemical properties) that I want to put through a PCA. Some variables have large units (e.g. %) and some small (e.g. mg C/L). Should I transform the larger units before running them through PCA? Some of the variables also have non-normal data; should I also...
  3. A

    Princ. component Analy. (PCA) wrong method for my data??? please help :)

    Hi there guys i'm facing a statistics Problem and hope you might be able to help me out. (sorry for my english it isn't that good) I want to analyse the Price of electricity in germany and have already bulid a dataset with 70 Variables (Solarproduction, Windproduction, Nuclearproduction and so...
  4. S

    Probability of Vehicles and Pedestrians meeting

    Hi, I need to produce a probability for a vehicle and a pedestrian meeting along a 1km road. Here is what I know: •1km road •cars take 3 minutes to travel •pedestrians take 12 minutes to travel •30 cars an hour •20 pedestrians an hour The cars and pedestrians may also be grouped or evening...
  5. T

    Minimum Accepted Sample Size for Tolerance Interval (confidence interval)

    Hi, I'm using the tolerance interval function in minitab, my sample size is limited to 7 (the parts are expensive blah blah) I've heard to be statistically significant a sample size of 30 is recommended but in practice how low can I go for sample size when using a confidence / tolerance...
  6. L

    Estimating Likelihood of NFL Game Outcomes

    Hey all, similar to last year, I'm passing along the tracker for the top 4 statistical model trackers for the season. Good news is that they are all at 100% so far...
  7. S

    Best statistical method for CFU/ml?

    I have sets of data in CFU/ml for different sampling sites collected in two different seasons. 1. How do I compare the CFU/ml between sampling sites within one season? 2. How do I compare the CFU/ml in different seasons of the same sampling site? one-way ANOVA?
  8. P

    Survival Analysis Alternative for disproportionately missing cases

    Hello everyone, I am new to the Data world and am facing a problem which I can’t seem to fix. My task is to analyze why some people cancel their policies and some don’t (find sig. factors) and to estimate the risk of cancelling for different groups. I was thinking of using survival analysis...
  9. L

    logistic student applied beloved stats

    Hi everyone, I get in touch with you to check my thinking procedure and my accuracy of stats knowledge which should be now quite low but I try my best even is not my mother language and my top quality topic I study logistics and I have so exam in stat for year 1 I guess after study I...
  10. K

    Measuring the effect of in-store Promotions

    Hello, I am testing the effect of a new in-store promotion technique (treatment). It is applied during product promotions, as a compliment to regular promo displays, to further improve sales. I have the treatment in only one store but on several products promotions in that store (I have...
  11. A

    Statistical inference

    Hi there, I would like to ask a couple of basic questions: 1. What is the difference between estimation and hypothesis testing? I mean are they two options for inference? or estimation of the parameters comes first and then we apply the hypothesis testing? 2. How can I determine what is...
  12. L

    Need Help with developing general linear mixed model regression equation

    general linear mixed model regression equation I'll be moving this to another thread and don't want to create multiple versions. Thanks!
  13. sepinaz

    Can we model the experiments as a stochastic process and estimate the sample size?

    I have an image with the size `5575x9440` and I'm implementing a modified version of the algorithm used in this paper on it, but because the code performance is low right now, I have divided the image to `52628` submatrices of the size `25x40 (1000 pixels)` and my first experiments show that...
  14. A

    HELP! Probability That Any Book May Be Read

    I have a question and I'm hoping people can impart some wisdom to my dilemma. My dilemma is lack of data to apply to this problem. The question I'm trying to answer is the probability that any book (in the English language) may be read by any Joe Bloggs. The reason I want to know is because...
  15. V

    mathematical model to build a ranking/ scoring system

    I want to rank a set of sellers. Each seller is defined by parameters var1,var2,var3,var4...var20. I want to score each of the sellers. Currently I am calculating score by assigning weights on these parameters(Say 10% to var1, 20 % to var2 and so on), and these weights are determined based on...
  16. J

    Regional analysis of disease risk factors

    I'm working with a large data set looking at climate variables e.g maximum, minimum temperature etc to see whether these could be risk factors for the regional variation for a sheep disease in 5 different regions within a country. The dependent variable is disease count (number of cases)...
  17. S

    vargha and Daleney A test ( to measure significance and direction)

    Hello As part of survey data. i conducting Mann whitney U test on ordinal data to identify the difference in ranking of dependent variable by independent variable . I have found significant difference in ranking by independent variable categories.. but i don't know the direction of the...
  18. C

    Statistical Significance Issue in Mixed Model

    A multilevel model, with one explanatory variable at the individual level (X) and one explanatory variable at the group level (Z): Y_{ij}=\gamma_{00}+\gamma_{10}X_{ij}+\gamma_{01}Z_{j}+\gamma_{11}X_{ij}Z_{j}+u_{0j}+u_{1j}X_{ij}+e_{ij} correlation between u_{0j} and u_{1j} is 0 . In this...
  19. C

    Notation of Variance of Residuals in Multilevel Modeling

    I am having some trouble to understand the notation of variance of residuals in multilevel modeling . In this paper "Sufficient Sample Sizes for Multilevel Modeling" , in p.87 below equation (3) , they mentioned " the variance of residual errors u_{0j} and u_{1j} is specified as...
  20. C

    Relative bias of estimates of multilevel logistic regression models

    The post is little bit lengthy , but it will give you thorough information and you can run the code easily . Trust me , I believe the answer is really very basic and not lengthy at all . I want to calculate relative bias of estimates of multilevel logistic model with one explanatory...