statisics

  1. A

    confusion on outliers

    I am not able to distinguish the outliers - When to go with std. dev and When do we need to go with Median. My understanding on std. dev. is - if the data is away from mean by more than 2 std dev. we consider that as outlier. Similarly for Median, we say that any data that is not in-between q1...
  2. N

    ANCOVA dilemma

    Hi All, Ive been given this question: Categorise the participants into high stress and low stress groups. Compare the two groups in relation to another psychological variable while controlling for a second variable. The data i have available (which i don't need to use all) is age, gender...
  3. C

    Finding Probability using z-table help

    The question is... Assume that the readings at freezing on a batch of thermometers are normally distributed with a mean of 0°C and a standard deviation of 1.00°C. A single thermometer is randomly selected and tested. Find the probability of obtaining a reading less than -0.976°C. P(Z<-0.976)=...
  4. T

    Please help with the following question

    A firm produces chains. The length of each link is independent of each other and normally distributed. The mean length of a link is 10. 95% of all links have a length between 9 and 11. The total length of each chain is the sum of the lengths of its links. You consider chains with 100 links 2...
  5. O

    Mann-whitney U test??

    What if I have two independent groups. In one of the groups age is normally distributed and in the other group age is not normally distributed. Which test should I use to analyze if there is a significant difference between the groups? Mann-whitney U test assumes both groups are not normally...
  6. K

    A quesion about Percentile

    This really drives me crazy, because i know its simple statistics. According to the World Health Organization (WHO), a child growth of age by weight should be like this : http://www.who.int/childgrowth/standards/tab_wfa_boys_p_0_13.txt you dont have to go into the link, here is a screenshot of...
  7. W

    Normal Distribution

    Assuming that the number of marks scored by a candidate is normally distributed, find the mean and the standard deviation, if the number of first class students(60% or more marks) is 25, the number of failed students(less than 30%marks) is 90 and the total number of candidates appearing for the...
  8. G

    Regression on two explicative variables

    Hello, I am currently doing a thesis which aims to explain returns of stocks in function of the ownerships of some stakeholders. In the Excel attached, I would like to explain the returns in the last column with the two explicative variables ( Venture Capital % Ownership and Hedge Funds %...
  9. S

    A statistic question.

    Provider Charge(Total) Fraud %Fraud Fraud*%Fraud A §§§§§§§1000§§§§§§§600§§§§§0.6§§§§§§360 B §§§§§§§100§§§§§§§§70§§§§§§0.7§§§§§§49 C §§§§§§§10§§§§§§§§§8§§§§§§§0.8§§§§§§6.4 D §§§§§§§1§§§§§§§§§§1§§§§§§§1.0§§§§§§1 Please ignore "§" above. Which provider should be given alert? I am...
  10. C

    Basic questions from newbie

    Hi, I am currently learning ML algorithms and implementing in R. I have a couple basic questions. 1.)Is dimensionality reduction same as feature selection? I know that in R specifying importance=T parameter in randomForest function gives you the important features based on info.gain.I was...
  11. S

    SPSS Help

    Hello everyone, I am a psychology undergraduate who has been set a formative assignment (which means its not worth anything but still has to be done) using SPSS. I was wondering if anyone could help me answer these questions as I am struggling and My lecturer scares me and isn't very nice. I...
  12. L

    Question about type of research

    Hello guys!:) I wonder whether anyone of you who is killing in statistics could give an advice. I am writing my master thesis at the moment. The first part of my research is planned to be focused on the sample of N oilservice firms, in other words, firms in the same industry. What i want...
  13. T

    Help with model Matrix GLM

    Hey guys been browsing the forums for a while, and usually find what I need! This is a tad more specific though so Ive made an account!! I've been puzzled by the form of the model for a while.. The model states that the response depends upon y~smoke + drink +smoke:drink +age:smoke. The model...
  14. B

    Could you please suggest a newbie about publishing Statistics related papers?

    Hello, I am quite new in writing and publishing papers. I have written a few papers, not that tough ones statistically, may be, but well written with properly performed analysis. One paper is on nutritional aspect of the country using a nationally representative data. There I have used a...
  15. M

    How to determine the accuracy of three combined tests

    Hypothetically, I have three tests that can determine if someone has cancer or doesn't have cancer. A True positive would indicate that the person doesn't have cancer. Below is a description of each test. Test 1: TP=.7 , FN = .3 , FP= .1 , TN = .9 , Accuracy = 80% Test 2: TP=.8 , FN = .2 , FP=...
  16. R

    Delta method

    I was wondering if anybody can help me as I've been stuck on this problem for ages and my attempts seem to all be incorrect so far. I have four estimators (W,Χ,Y,,Z) and standard errors for each. How can the standard error of D be cacluated from the following equation, where K, and L are...
  17. G

    One Factor Repeated Measures ANOVA questions

    Hi all, I have conducted a repeated measures ANOVA that has one factor with two levels. I also have a one between-subjects factor that has been taken into account. The results have come back to say that there is a significant difference between the within-subjects factor. My question...
  18. Z

    How do I interpret regression coefficients when there are log transformations?

    Hi, I'd like to know how to interpret with percentage the slope coefficients of a regressoin when I have: A- log(Y) ~ log(X) b- log(Y) ~ X c- Y ~ log(X) So far I found this web site, but I'm not sure it is accurate: http://www.ats.ucla.edu/stat/sas/faq/sas_interpret_log.htm...
  19. V

    What test to compare bacterial growth in three areas with repeating variables?

    I have a dataset of number of bacterial colonies grown from 11 water samples taken from 3 different watersheds. I want to know if the land area, population, number of waste water treatment plant outfalls, and number of septic tanks in the watershed have any effect on the bacterial growth. The...
  20. E

    finite Mixture of exponential in matlab

    Hi all can any body here help me with ((finite Mixture of exponential in matlab)) I want to simulate it in matlab or R for any given data ?