statistics

  1. D

    Differences in direction of association in univariate and multivariate analysis

    Hi, I have a question regarding results from univariate and multivariate analysis. I have found a positive association between a dependent and an independent variable in a univariate analysis. However, in the multivariate, after controlling for covariates, a negative association has been...
  2. M

    Prediction using Support Vector (SV) method

    Dear Friends, I came to know that using SVM method we can predict the future value more accurately than other normal methods (like ARIMA). My question is how do we give the future index value (let's say 101 when we have 100 values in a time series) so that we can get the predicted value for the...
  3. I

    Sample size for superiority trial

    Hey statistigeniuses, I would greatly appreciate some advice regarding a trial I am designing. I want to determine the most comfortable among 4 different materials. Each of these materials are applied to a person's skin at the same time and they are given a questionnaire to evaluate its...
  4. I

    Recommended books/resources for Campaign analytics

    Hi all! Could anybody please recommend any books, or other resources, from which I can learn Campaign analytics? I have gotten some hold of the basics of Campaign analyses (such as the importance of control groups, and KPIs like ATF, ATV), but I would like to learn more. Links to any...
  5. S

    Need a way to rank the products from data

    Hi All. I have a set of data for different products. I want to grade the products from 1 to 4. With 4 being the best. Please tell me how to do it? For the data below: 0 means best product and 8.95 means worst product. Product A = 8.95 from Manufacture A Product A= 0 from...
  6. L

    statistical symbols in microsoft word

    I've spent like 5 hours trying to figure out how to insert a bar (called overstrike or overline) over a word ... like the bar that goes over x for "mean" ... but I have to put the bar over the word "pred" in the results section of my dissertation. I've tried to use the formula function but when...
  7. A

    Statistical Study Help

    Hi, would someone mind reading this study and explaining the statistics used and some of the graphs and charts? I'm only in an introductory statistics class so I'm not familiar with all the statistics in this study. http://www.nature.com/ijo/journal/v30/n9/full/0803279a.html Thank you!
  8. K

    How do you know if you're making a Type I or Type II error?

    Type I and II errors seem really theoretical. In real life, how would you ever know if you're making a Type I or Type II error? Can anyone provide any practical examples of where someone doing social science research has found out they've committed one of the two errors?
  9. A

    How do you find equally likely possibilities?

    I have attached a homework problem to this post. It asks what the probability is that all 4 watches of a selection are inaccurate when the manufacturer claims that .05% of all its watches are inaccurate after a year. This is where I get so tripped up, I know that Probability is # of...
  10. W

    2 Coops and Chickens problem

    Hi, I have a question as homework to solve, but although it's so easy (as everyone says) I am not still able to solve it. Could you please help me with that? We have two coops: in coop 1 there are 10 male and 5 female chickens. Coop 2 has 5 male and 10 female chickens. We randomly select...
  11. K

    What type of distribution is this and am I being sensible?

    I have a computer model, which I need to run 3500 times with different input parameters. The model's accuracy depends on a constant, let's call it T, which unlike the input parameters doesn't change between model runs. By decreasing T, the model's accuracy improves but the computational cost...
  12. O

    Help with confidence interval and interpreting data!?

    Someone please please help me make sense of these stats! I really need help with interpreting outcome of studies! How do i calculate CIs (no need to know actual calculation as can use calculator) and make sense of outcome... Any help would make me forever grateful! STUDY 1. Pre- and...
  13. A

    ANCOVA woes

    I'm having real trouble interpreting the output from my ANCOVA. I have two conditions control and experimental, my dependent variable is state self-esteem and my covariate is trait self-esteem. In the model I have included gender and condition as a fixed factors and the covariate as trait...
  14. B

    Help with ANOVA Analysis of Data

    I need to compute: The sum of squares associated with sex from the ANOVA table; Create histograms of the data used in the ANOVA for each level of Sex independently. Using this output and boxplot and apply do you think the assumptions of ANOVA have been met? How do I input the data of...
  15. B

    T-Test Help

    Hi I am totally new to stats and finding it very difficult. I was wondering whether or not anyone could help me understand which T-Test to use to try to see if my results are statistically significant. I'll try to explain the situation. I have 8 sub groups, which make up two main groups (A...
  16. C

    Computing the test statistic: Not sure which Formula I need

    Not sure which formula to use... A Health and Fitness company would like to determine if a new product improves cardiovascular fitness. A sample of 20 new customers agreed to take a treadmill test before and after using the product. The test measured how long they could run on the treadmill...
  17. S

    Seemingly unsolvable conditional probability

    The following is a question that is likely to be appear on my exam on Friday (tomorrow) but contextualised into a different scenario. I'm having serious difficulty figuring out how to go about answering it. If anybody has encountered something similar and could provide a step by step explanation...
  18. A

    Picking the correct test, need help urgently!

    Hello, I feel like the answer for this is probably really obvious but I am being missing it altogether. This is my data: Habitat Associating Not Associating Total Observations Flood 51 0 51 Levee 524 72 596 Liana 162...
  19. M

    Data input into SPSS: What happens if there are more treatment data sets than control

    Hi guys, I am currently on the results section of my dissertation in Sports Science and I am having trouble completing my two-way repeated measures ANOVA due to data input complications. I have searched the internet and had my head in a few books but I am yet to find anything. Basically in...
  20. A

    Similar numbers in a data set

    Hi guys, I am looking at a programming problem here, and would like to "deduce" a formula out of my problem. I have an array of n (known) columns and two rows. I populate this array with number in a range (1 to n) let's say 1 to 5 for the example. 1 3 2 5 1 n 2 4 1 4 2 n What I...