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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: 18,746
10-11-2014, 12:02 PM
1. ### Variance Inflation Factor

Hej, I am checking for multicollinearity. And I cant find on the web when having the outpur from R commander, on which I have to look to identify...

• Replies: 10
• Views: 5,032
10-02-2016, 06:38 PM
2. ### gender differences

Hi, I have a daily information for years about a dependent variable that measures the degree of risk taken by men and women in their decision...

• Replies: 6
• Views: 5,031
05-09-2009, 07:40 PM
3. ### Accelerated Bootstrap - mediation

Howdy! :tup: Can anyone explain accelerated bootstrap to me? I've got it reported in a research report and I can't really figure it out. ...

• Replies: 2
• Views: 5,025
08-20-2011, 04:15 PM
4. ### T-Test: How large is large?

I'm doing some research, I collected data from two different groups, 80 samples in each group. The data is borderline for normality. I've read on...

• Replies: 1
• Views: 5,001
12-18-2009, 03:14 AM
5. ### statistics calculator to adjust for design effect

Hi there, I'd like to know if anyone could tell me of a stats calculator that can adjust means and confidence intervals of analyses (paired-t and...

• Replies: 1
• Views: 4,990
07-01-2010, 02:41 PM
6. ### Strict and Weak Stationarity Tests

Hello, As far as i know stationarity can be characterized as weak and strict. The most well known test for stationarity are Dickey Fuller,...

• Replies: 2
• Views: 4,989
11-06-2011, 06:24 PM
7. ### item-scale correlation

Hi, When running an item-scale correlation, what does it mean when research have corrected for overlap? Is there a way to do this in SAS?

• Replies: 13
• Views: 4,958
10-21-2014, 12:19 PM
8. ### How to generate an autocorrelated random variable?

Hi, I know I can generate two correlated random variables x1 an x2 using x1= z1 x2= c* z1 + sqrt(1- c^2)* z2 Where z1: standardnormal...

• Replies: 15
• Views: 4,958
03-11-2015, 01:08 PM
9. ### Longitudinal analysis and the independence assumption

This is a bit of a long one, but I would really appreciate some help with it. I have a long list of data which describes whether a violent...

• Replies: 9
• Views: 4,954
11-13-2011, 05:14 PM
10. ### Cross sectional T-test, event-study

Hello, I'm new to the forum and I have tried searching for it but couldn't quite find my solution. I'm working on a paper involving an Event study...

• Replies: 0
• Views: 4,949
01-27-2014, 07:09 PM
11. ### Bayesian inference, MAP and sampling (Gibbs)

Hi all I'm applying bayes inference to a GMM, based on some data set. I'm using Gibbs sampling to get the "samples" from the posteriors (the mean's...

• Replies: 6
• Views: 4,946
04-17-2011, 09:30 PM
12. ### In dire need of help!

I took Stats 1 3.5 years ago and somehow the college forgot to mention i needed stats 2 to graduate and am now in it. I AM SO LOST and I have a...

• Replies: 3
• Views: 4,926
01-27-2012, 05:01 AM
13. ### studying half-hourly time series

hello, I have to study a time serie composed of half-hourly data concerning electric load for the period of 6 years : so in my file data i have...

• Replies: 5
• Views: 4,907
02-24-2009, 03:05 AM
14. ### How to compare data from different periods

I want to analyze the performance of two groups of organizations over time (year to year), using existing information. The groups are similar,...

• Replies: 0
• Views: 4,906
10-14-2009, 12:43 PM
15. ### Best design for this experiment?

Hello all. I am having some trouble with my experiment and would be the best way to analyze the data. I have 4 different chemicals each at one...

• Replies: 16
• Views: 4,906
08-26-2011, 04:55 PM
16. ### Infinite divisibility under mixing - kernel density estimation

Hi all, Can we consider a (multi-modal) kernel density estimate as a finite mixture of probabiliy distributions which would be infinite divisible?...

• Replies: 3
• Views: 4,874
08-18-2008, 12:07 PM
17. ### Mixed positive and negative correlations in a mediation model

Can you offer any potential explanations for the following: Significant positive correlations between A and B, & B and C, but a significant negative...

• Replies: 0
• Views: 4,864
11-20-2010, 04:08 PM
18. ### interval censored data using bootstrap method

I have time Xi that is interval censored and the data consist of time intervals Ii = such that Xi is within Ii , Ri>Li, i=1,...,96 My interest is...

• Replies: 2
• Views: 4,852
03-29-2011, 09:09 PM
19. ### xtDPDsys postestimation

Hi all I run two equations using xtdpdsys, the postestmation came as follows First equation estat sargan Sargan test of overidentifying...

• Replies: 0
• Views: 4,823
03-19-2011, 05:37 AM
20. ### Question re: maximum observation value falling in third quartile

:wave: You all have been my saviors in the past whenever I've been stuck with my stats. I need to figure how I interpret the fourth quartile...

• Replies: 4
• Views: 4,816
12-16-2010, 10:23 AM
21. ### No collinearity between dependent and exogenous variables - Implicatrions

I'm trying to test for autocorrelation in the residuals of an AR(p) model. The stata output is: "the exogenous variables may not be collinear with...

• Replies: 0
• Views: 4,811
05-04-2013, 11:54 AM
22. ### PCA latent variables

For exploratory purposes, should PCA (Principal Component Analysis) be done for one latent variable at a time or should it done for all the latent...

• Replies: 3
• Views: 4,808
04-25-2011, 09:33 PM
23. ### ANOVA and quadratic terms?

Hello everyone! I have what I think is a relatively straight-forward 3-way factorial ANOVA design. One of my factors (which is "number of...

• Replies: 7
• Views: 4,801
01-21-2013, 11:33 PM
24. ### Anova

Develop two-null hypothesis tests to ascertain if there are any statistical variances in the averages of bus route times and any statistical variance...

• Replies: 2
• Views: 4,792
09-02-2008, 03:38 AM
25. ### Is online survey random? How to make it random?

Hi there, I want to conduct an online survey. I know that by default only some users would be included. How to increase randomness? Thank you.

• Replies: 2
• Views: 4,787
12-25-2010, 06:14 AM
26. ### Calculating weighted mean & SD from multiple group data

I have a query regarding the calculation of a weighted mean +/- standard deviation based on a set of group data containing means and standard...

• Replies: 2
• Views: 4,773
asf
11-21-2012, 07:47 PM
27. ### Can I use standard deviation in Likert scale (1-7) data with non normal distribution?

I have 20 questions, each divided in 6 Likert scale items (1-7), representing 6 different values like Success, Oportunity, etc. The sample is rather...

• Replies: 3
• Views: 4,772
12-31-2012, 05:39 PM
28. ### Complementary log log

Hi I have a model with a binomial error distribution. Instead of the logit link I use the complementary log log. What is the interpretation of...

• Replies: 1
• Views: 4,771
02-12-2009, 04:09 PM
29. ### Comparison of the power of the tests: Parametric test versus Non-parametric test

How can one compare using a simple experimentation or simulation whether a parametric test (e.g. t-test) is more powerful than its non-parametric...

• Replies: 6
• Views: 4,764
08-26-2012, 04:23 PM
30. ### Correlation Between Unpaired Data?

What type of statistics compares or finds correlation of unpaired data? I'm assuming an XY scatter plot wouldn't work. I'm also assuming a t-test or...

• Replies: 4
• Views: 4,725
08-27-2013, 12:15 PM
31. ### Tails and QQ Plot

Does Anybody know if exists a formal proof about the well known properties of the qq plot? "families of symmetrical distributions with tails heavier...

• Replies: 0
• Views: 4,722
08-31-2011, 08:42 AM
32. ### Repeated Measures with a baseline Covariate

I am in the final stages (i.e., manuscript is due on July 21) of my dissertation and I am stuck on what seemed to be a minor stats issue. This issue...

• Replies: 0
• Views: 4,721
07-06-2009, 02:46 PM
33. ### Jackknife

I tried to find a specific example of an application of the 'jackknife' command on google, but didn't find any so far. Someone has one? For...

• Replies: 2
• Views: 4,717
03-15-2009, 10:11 AM
34. ### Difference between DBLIM and distance-based redundancy analysis???

Hey there statistical wizards, I have been conducting some statistics using Primer on some ecological data incorporating environmental...

• Replies: 1
• Views: 4,717
07-17-2011, 06:07 PM
35. ### Statistical question about roulette

I was wondering if anyone could help me with a statistics question I have? It would be great if anyone could look at this one. It is based on...

• Replies: 5
• Views: 4,710
BGM
06-13-2011, 04:37 PM
36. ### DF in Repeated Measures ANOVA

Hi all! :wave: In advance: thank you to all those who take the time to even read this post, as well as answer it: Additional to my sunfish study...

• Replies: 0
• Views: 4,703
02-08-2011, 12:23 AM
37. ### Why use Chi-square?

Hi, I am putting together a statistics course about inference techniques to use when the predictor variable(s) are categorical (by which I mean,...

• Replies: 9
• Views: 4,686
08-15-2012, 01:58 PM
38. ### Urgent, which test can I use to test this hypothesis???

Hi all, please help me I am stuggling doing my data analysis of my poject and my supevisor is on holiday but I have to finish all the ananlysis in...

• Replies: 18
• Views: 4,684
07-17-2011, 05:16 PM
39. ### Low or high correlation?

What does it mean when Pearson correlation gives a value of 0.7-0.8, while spearman correlation gives a value from 0.3-0.4? Pearson reports high...

• Replies: 7
• Views: 4,684
03-13-2014, 09:16 AM
40. ### Repeated measures ancova

Hi I am very stuck does anyone know how to run a repeated measures ancova in spss please!!!!

• Replies: 1
• Views: 4,680
06-09-2010, 05:19 PM
41. ### Dichotomous data...

Could you tell me if you can use ANOVAs on dichotomous data (specifically "yes" / "no") responses? If not, what other options do you have if your...

• Replies: 1
• Views: 4,675
08-21-2009, 01:41 PM
42. ### Help needed - estimating effect size

Hi everyone, I'd really appreciate any help/guidance in solving a little problem of mine. I need to know how to estimate an effect size...

• Replies: 3
• Views: 4,674
08-05-2008, 02:00 PM
43. ### Need some help choosing correct statistical method for study

Hi. I'm about to carry out a study and require suitable statistical method(s) for it. I plan to measure the effect of fluoridation on the growth of...

• Replies: 2
• Views: 4,674
03-27-2011, 02:56 AM
44. ### Meaning for variants of Standard Deviation

Could someone explain the meaning of the following: 1. More than 3 SD? 2. Less than 3SD but more than 2 SD? 3. Less than 2SD but more than 1 SD?...

• Replies: 0
• Views: 4,657
09-18-2009, 12:06 AM
45. ### Calculating abnormal returns with the calendar time portfolio approach

Hey guys, I want to conduct an event study and since there is a lot of overlapping of the observation windows, I want to use the calendar time...

• Replies: 0
• Views: 4,649
09-20-2013, 03:19 AM
46. ### Project ideas

Hello guys and girls, In our coursework programme we will be asked to complete 2 industry projects each 25-30 pages long. There is a great number...

• Replies: 0
• Views: 4,644
11-28-2010, 06:07 AM
47. ### Help Anova

hi everyone, I currently try to find an open source C/C++statistical library. Basically, I want to calculate the p and F value from oneway (or N...

• Replies: 11
• Views: 4,639
12-14-2005, 05:55 PM
48. ### Feedback on bootstrapping effect size and t-values

I am trying to learn to bootstrap per conversation here the other day. I know there are packages to bootstrap but wanted to process more...

• Replies: 31
• Views: 4,639
04-28-2015, 09:25 PM
49. ### Minimum sample size for calculation of guttamns lower bounds?

Hi there, I am in the process of assessing the internal consistency of two tests, test A & B. Both tests are measuring the same thing so I am...

• Replies: 3
• Views: 4,632
10-11-2011, 07:37 PM
50. ### Structural Equation Modeling: When and why do you use Z-scores instead of Mean.

Hi. Can anyone help me answer the question why some people who do SEM use z-scores as opposed to using mean scores? (articles and books are...

• Replies: 4
• Views: 4,631
01-15-2015, 11:27 AM
51. ### Extreme events...

Hi. Is {w:P(w) is very small} acceptable to translate the meaning of extreme events given in the following sentence: An extreme event is defined as...

• Replies: 6
• Views: 4,630
07-14-2010, 07:47 PM
52. ### Significance of Correspondence Analysis clusterings

Dear All, I would like to ask you about Correspondence Analysis. I am wondering if does any strategy exist to test the significance of the...

• Replies: 4
• Views: 4,614
01-03-2010, 02:27 AM
53. ### Calculate SD from mean and 95% CI

Dear Friends I'm reading a paper that has the following table: Year, n, measure (SD) 2008, 536 0.25 (0.13) 2010, 536 0.21...

• Replies: 7
• Views: 4,611
10-03-2012, 06:31 PM
54. ### State the null and alternative hypothesis

Dear all, Can someone please give me some advise on this one? I need to state the Ho en Ha hypothesis, I know how to do it in words but not in the...

• Replies: 5
• Views: 4,597
11-16-2014, 01:09 PM
55. ### low coefficient alpha

Hello, I have a question about coefficient alpha. How does having a low alpha effect your statistical tests if you are running say an ANOVA or a...

• Replies: 0
• Views: 4,585
05-19-2009, 11:19 AM
56. ### Obtaining Residuals in Chi Square Goodness of Fit

Another question re: goodness of fit testing, Is the procedure for obtaining standardized residuals the same ? The PhD student who leads the...

• Replies: 4
• Views: 4,572
04-28-2009, 11:01 AM
57. ### minimum data points for the K-s test for normality

Dear all I have 6 points of data that i need to test for normality. is this enough to use the K-s test? what is the advised minimum for this test?...

• Replies: 0
• Views: 4,572
08-18-2010, 04:45 PM
58. ### Which Anova to use???

Okay. So I've read tons of books on this and none of them seem to give me a clear answer so here goes. I have 40 subjects. Each will be randomly...

• Replies: 2
• Views: 4,570
01-31-2011, 03:01 AM

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