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# Forum: Statistical Research

Statistical theory and methodology. Mathematical statistics. Parametric inference. Nonparametric inference.

1. ### Sticky: Proof of the day

In this thread we post one (or more if you can't wait) proof a day. I'll start by proving the that V=\sigma^2(X'X)^{-1} in the linear...

• Replies: 14
• Views: 18,683
10-11-2014, 12:02 PM
1. ### Need help defining terms for mixed model nested ANOVA

Hello - I am looking at the effects of restoration practices on a suite of environmental soil parameters through time. I am having trouble defining...

• Replies: 5
• Views: 2,864
07-16-2012, 04:59 PM
2. ### simple multivariate question

I have, I think, a simple question about multivariate statistics, and I'm not sure which test (or even what kind of test does this). I have 40...

• Replies: 7
• Views: 2,393
07-16-2012, 03:46 PM
3. ### Doubts analyzing Likert scales

Hi all, I thought about analyzing results from Likert scale using Kruskal-Wallis, but the more I read about it, the more confused I get. People...

• Replies: 3
• Views: 4,513
07-12-2012, 09:01 PM
4. ### Test of Significance advice needed

I'm currently in high school doing my IB. I've been sifting through hundreds of CAT scans and x-rays that have been kindly donated to me by various...

• Replies: 7
• Views: 2,061
07-12-2012, 07:48 PM
5. ### Logistic regression question on outcome variable

I have a large database with more than a million records. I would like to study the impact of several predictor variables (age, race, etc) on one...

• Replies: 0
• Views: 1,551
07-12-2012, 07:08 PM
6. ### Multiple t-tests versus ANOVA RM 2 way

Hi there, A standard textbook comment when you read on performing multiple t-tests instead of doing an ANOVA study will say, "performing multiple...

• Replies: 1
• Views: 2,041
07-12-2012, 01:08 PM
7. ### Fisher's Exact test significance, APA results phrasing

My original post questions were answered offline. Thanks for allowing me to post!

• Replies: 0
• Views: 2,288
07-10-2012, 10:42 PM
8. ### Kruskal Wallis test and problem with zeros

Hi. I am conducting a biological research about species abundance variations between different hours and localitions. I am comparing 11...

• Replies: 0
• Views: 3,038
07-09-2012, 07:19 PM
9. ### manifold data/ cluster data

what is the difference between manifold data/ cluster data??

• Replies: 0
• Views: 1,459
07-06-2012, 12:28 PM
10. ### STDEV at Different Means

Im trying to measure 'consistency' in baseball scores amongst two different sample groups. For example, in a sample of 162 games each, one team...

• Replies: 1
• Views: 1,146
07-06-2012, 11:36 AM
11. ### Rule Associations Help

I apologize in advance if this is the wrong section. I'm trying to discover rule associations for a survey with over 140 attributes. All of the...

• Replies: 2
• Views: 1,475
07-05-2012, 10:49 AM
12. ### interaction between highly correlated variables possible?

Dear all, maybe someone can help me. I ve read up on the interaction-topic, but I m confused. I have an interaction between a categorical and...

• Replies: 0
• Views: 1,666
07-04-2012, 09:19 PM
13. ### research question

easy (stupid?) question. for a small project, i had to write a research hypothesis and null hypothesis research hypothesis. the research...

• Replies: 1
• Views: 1,401
07-02-2012, 08:53 AM
14. ### Correlation of Distances

I am trying to measure geometrical similarities of given two time-course data. Each of two time course data measures independently something changing...

• Replies: 0
• Views: 1,472
07-02-2012, 06:36 AM
15. ### how to control for firm performance ? (control variables) ?

I'm doing a research on how the debt ratio affect firm performance dependent variable is ROA independent variable is debt ratio control variable...

• Replies: 0
• Views: 4,377
07-01-2012, 08:44 AM
16. ### Looking for suggestions on proposed research questions

Are my questions worded succinctly? Can you think of other information that could be gathered in order to determine whether CEO involvement...

• Replies: 1
• Views: 1,657
06-29-2012, 08:46 PM
17. ### What kind of evaluation is appropriate for my project?

I had a randomized clinical trial with two treatment groups and one control group, measurements at pre-test, post-post, for each of the three...

• Replies: 1
• Views: 1,470
06-29-2012, 02:46 PM
18. ### How robust is ANOVA's F-statistic?

Hello there! I have theoretical question about the robustness of the F-statistic used in ANOVA when used on data that is negatively skewed. Many...

• Replies: 3
• Views: 3,198
06-29-2012, 01:48 PM
19. ### dummy*continous interaction- sig. main effect, non-significant interaction

Hi all, I would be grateful if someone could give me advice on the following topic: I estimated a glm and formed an interaction term out of a...

• Replies: 0
• Views: 1,822
06-28-2012, 05:33 PM
20. ### interpreting SS in permutational (M)ANOVA with adonis

Dear all, I want to use the adonis() function in R package vegan to do a permutational univariate analysis of variance (instead of multivariate)...

• Replies: 0
• Views: 2,730
06-28-2012, 10:46 AM
21. ### Multiple comparison tests with no ANOVA

Hiya, I've tried to find an answer to my question by searching the net but I can't find any clear solution. I want to compare the effect of...

• Replies: 0
• Views: 1,501
06-26-2012, 11:56 AM
22. ### How to compare repeated measurements

deleted and moved to biostatistics forum

• Replies: 0
• Views: 1,367
06-25-2012, 01:50 PM
23. ### Class interval identification problems!

My data is transport cost (in percent) of 60 companies I decide to divide it into 5 classes (very good, good, moderate, poor, very poor) as the...

• Replies: 0
• Views: 1,512
06-24-2012, 06:11 AM
24. ### Paired t-test VS Anova

I'm reading an article which is comparing the effects of three variables. But the authors used several paired t-tests to measure two variables at a...

• Replies: 2
• Views: 3,285
06-22-2012, 06:37 PM
25. ### Multiple Group Analysis necessary?

Hi, for my master's thesis I collected data with an online survey, measuring consumer behaviour. I used two samples, one group from Australia and...

• Replies: 13
• Views: 16,182
06-22-2012, 03:05 PM
26. ### Consistency in statistical tests

Hiya, this is quite a basic question. I'm testing whether administration of a drug causes an increase in 7 different dependent variables. So my...

• Replies: 1
• Views: 4,040
06-22-2012, 02:47 PM
27. ### Comparing confidence intervals: CI of mean vs CI of regression coefficient

Hi, I have longitudinal data with measurements at two timepoints. I am interested in the change per year and calculated this in two ways: *...

• Replies: 0
• Views: 1,831
06-22-2012, 08:28 AM
28. ### What type of sampling is this?

Hi, I have some confusion about the kind of sampling I'm using. I started choosing manufacturing sector and within it chose 4 industries. Later I...

• Replies: 6
• Views: 2,276
06-21-2012, 10:30 PM
29. ### Appropriate form of ANOVA when blocking

Hi, I'm new to this forum (and relatively new to statistics) and have a question :) I have a text book that outlines the following experiment: ...

• Replies: 3
• Views: 1,640
06-21-2012, 03:51 AM
30. ### does the following interaction make sense?

Hello, I have a problem, it would be great if someone could help me with it. I m analyzing a sample of patients with eating disorders (anorexia ,...

• Replies: 0
• Views: 1,346
06-21-2012, 01:12 AM
31. ### Test of a given distribution against specified percentiles

Hello all. Is there a way to conduct a test say, 5th, 95th percentiles, median, and quartiles against a parametric distribution (e.g. zero...

• Replies: 1
• Views: 1,721
06-20-2012, 05:16 PM
32. ### Statistical analysis for Rubric Based Research

There are 26 participants who have participated in my research. Each participant treated with a lab module (Hands on Robotics Session). Now each...

• Replies: 3
• Views: 2,964
06-17-2012, 08:48 PM
33. ### Combing Posterior Probability

Does anyone know any methods that are used to combine two posterior probability obtained from different classifiers ?

• Replies: 1
• Views: 1,630
06-14-2012, 01:09 AM
34. ### 3 interdependent variables, parametric fit, loss for words

I'm looking for a mathematical description of a data-set, but i have trouble finding the right wording. So i will just describe the situation. I...

• Replies: 0
• Views: 2,374
06-13-2012, 05:29 PM
35. ### Confidence interval for (Xbar-2*Ybar)

Hi, Can any body help me to calculate confidence intervals for (Xbar-2*Ybar), where X and Y are two random variables. Is this as simple as (Xbar -...

• Replies: 2
• Views: 2,310
06-13-2012, 11:06 AM
36. ### Plsr

I know PLSR can deal with multiple dependent variables, how about if let say the 2 dependent variables are totally no relation at all, shall we do...

• Replies: 2
• Views: 1,505
06-12-2012, 11:57 AM
37. ### Factor Analysis

I plan designing a questionnaire. The fact is the questions asked involving nominal variables and open ended question. Can I proceed factor analysis...

• Replies: 0
• Views: 1,154
06-12-2012, 02:32 AM
38. ### Hypothesis Testing

Hello , I have the following Null Hypotheses : There is no value grater than 20 If I have a population :...

• Replies: 4
• Views: 2,292
06-11-2012, 06:49 PM
39. ### More measurements to reduce CV% in RIA?

Hi, everyone! I got quite high CV% between many duplicates in my radio immunoassay experiment. I run the samples again and some results were much...

• Replies: 0
• Views: 2,938
06-11-2012, 08:15 AM
40. ### Would you help me? (Tranformations)

Hi, I was looking for tranformations for ratio data. I find that arcsine tranformation is adecuate for that kind of data (ratio). For that...

• Replies: 15
• Views: 5,292
06-06-2012, 09:07 AM
41. ### Two stage least squares estimation

Hello, I am a researcher in the sciences and trying to determine the validity or well-groundedness of a particular technique I see a lot. I am...

• Replies: 0
• Views: 2,138
06-05-2012, 12:35 PM
42. ### How to classify data into group?

I have collected warehousing cost data from 200 companies...and then converted to % There are 200 data (lowest from 1.5 % to highest of 40 %). My...

• Replies: 5
• Views: 3,838
06-05-2012, 07:54 AM
43. ### How does sampling reduce selection bias?

Hi everyone, I'm struggling to understand theoretically how sampling reduces selection bias. Take the following example: Supposing there is a...

• Replies: 1
• Views: 5,115
06-04-2012, 08:32 PM
44. ### How to combine Probability Distribution Function of Two correlated variables?

I have the probability distribution Functions(PDF) of the wind speeds of two wind sites which have a certain Pearson's correlation coefficient. How...

• Replies: 0
• Views: 2,743
06-04-2012, 05:21 PM
45. ### Need help on SEM analysis using AMOS

After defining my model when I run the analysis, it gives me a message that "The specified model is probably unidentified. In order to achieve...

• Replies: 1
• Views: 13,356
06-04-2012, 12:31 PM
46. ### Chi square test for ordinal variables

Hey all, I have a question regarding the chi-square statistics. I have a total sample size of more than 4,000 and I have 2 groups (2 different...

• Replies: 3
• Views: 4,006
06-03-2012, 04:38 AM
47. ### Regarding ANOVA for demographic variables

Hi, In my research, i asked for demographic information related to age, marital status etc. Also, I collected information for who takes buying...

• Replies: 0
• Views: 2,314
06-02-2012, 03:17 AM
48. ### Could anyone recommend an interactive application for mass data analysis?

Hi, everybody I need to conduct a large amount of data analysis on database. Could anyone recommend an interactive application for data analysis?...

• Replies: 13
• Views: 3,102
05-31-2012, 09:25 PM
49. ### Correlations between groups of Likert-type answers – choice of statistical test

I'm looking for the optimal way to interpret some data, so any constructive advice will be appreciated. A questionnaire with 3 groups of 50...

• Replies: 1
• Views: 41,277
05-31-2012, 05:02 PM
50. ### Easy Standardization Question

Hello everyone, I have a hopefully solveable question, however, I would like to get your opinion on it, as I am not 100% sure. I have a dataset...

• Replies: 0
• Views: 1,316
05-30-2012, 04:15 AM
51. ### What is the point of providing p-values for baseline characterisitics?

I just have a general question about what the point is of have baseline characteristics and then presenting p-values for these. Is the p-value...

• Replies: 3
• Views: 8,268
05-29-2012, 02:13 PM
52. ### comparison of Exponential distribution and Lognormal Distribution parameters

Hi everyone! I have 30 days worth of data. Each day, I have a set of interarrival times. I wanted to find out the distribution of the arrivals, so...

• Replies: 0
• Views: 3,634
05-29-2012, 07:07 AM
53. ### Student -T with big sample

If the population variance is unknown and the sample size is >30, can I proceed to use Student-T to compute confidence interval ? or I have to use ...

• Replies: 7
• Views: 2,377
05-28-2012, 02:04 AM
54. ### Stratified Random Sampling

If the population size for each stratum is unknown and cannot be measured ? Can I still utilize this sampling procedure ? How to estimate the...

• Replies: 4
• Views: 2,572
05-27-2012, 10:18 PM
55. ### PLS-DA: Are latent variables comparative?

Hello, first post on the forum - hopefully this is the correct place to do this. I've been working on developing an system for visualising the...

• Replies: 2
• Views: 3,439
05-27-2012, 07:40 PM
56. ### how to interpret interactions when one variable is in a log scale?

Hi there, I have a significant interaction in the model and was wondering how to interpret the coefficient given that one original effect is in a log...

• Replies: 1
• Views: 1,334
05-27-2012, 02:42 AM

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