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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: 18,731
10-11-2014, 12:02 PM
1. ### One Sample T-Test with Likert Scale Questionnaire

Hi all, I am doing a research and will study the how user think about shopping online. In my questionnaire, I have 3 questions - using Likert...

• Replies: 8
• Views: 66,500
12-17-2016, 02:18 AM
2. ### Factor Analysis vs. Principal Component Analysis

I've asked this question on here a while back but didn't quite get an answer that helped me understand what is truly different about these two...

• Replies: 8
• Views: 4,158
01-09-2013, 07:31 PM
3. ### Need urget help for one sample z test of proportions

Hi All, I need to confirm whether I am doing it correctly. Survey question is: Have you ever witnessed violent episodes/incidents in the...

• Replies: 8
• Views: 1,839
02-14-2013, 05:42 AM
4. ### Regression

Hi All, I have a quick question about the correlation before conducting regression. If there was no correlation between x and y, is there any...

• Replies: 8
• Views: 1,434
04-12-2013, 03:12 PM
5. ### How to compare multiple testers wine ratings?

Newbie alert! Problem description: I have 20 wines and 6 tasters. Each taster ranks the wines from 1 to 20. Question: How do I test the...

• Replies: 8
• Views: 1,481
06-25-2013, 07:48 AM
6. ### normal distribution

I tried three transformations (LG10, SQRT, rank transformation). But I couldn't make the data normally distributed. Could you kindly let me know if...

• Replies: 8
• Views: 2,082
09-04-2013, 06:54 PM
7. ### Unable to determine the right test?

hello, I'm doing a paper on measuring authors productivity and unable to decide what should I use as my statistical test to come up with solid...

• Replies: 8
• Views: 2,393
10-20-2013, 01:09 PM

I got a negative adj. r-square. Since the effect size (Adj R-sq=-.016) was low, did it indicate that a time in treatment (the independent variable)...

• Replies: 8
• Views: 3,159
05-02-2014, 05:10 PM
9. ### Need help with Multiple Imputations ("pooled" dataset)

Hello everybody, My original data set (n=901) contains missing values (10-20% per variable). I am applying Multiple Imputations technique using...

• Replies: 8
• Views: 3,935
06-23-2014, 02:07 PM
10. ### Are they misunderstanding ANOVAs here?

Hi, Here's an extract from a paper I'm using in a systematic review: The mean GAD-7 score of the sample prior to the course was 10.98 (SD 5.17,...

• Replies: 8
• Views: 2,466
10-24-2014, 11:22 AM
11. ### Looking to hire freelance statistician

I'm sorry if this isn't the right thread to post this question, but here goes. I'm looking for a statistician to do some freelance work, but I'm...

• Replies: 8
• Views: 2,258
11-13-2014, 01:07 PM
12. ### mean+standard deviation+skewness+kurtosis

hi I want to order some variables according to (mean+standard deviation+skewness+kurtosis) or some new rule considering mean value, standard...

• Replies: 8
• Views: 2,480
03-06-2015, 02:25 PM
13. ### What to do when survey participants answer all '4's?

I reached out to members of my organization to rank how they felt the company was performing on various topics, about 35 questions in total. Several...

• Replies: 8
• Views: 1,600
07-09-2015, 12:24 PM

I work for a company that sells products online. I am attempting to create a common sense SOP for our email marketing campaigns and have plenty...

• Replies: 8
• Views: 1,914
10-22-2015, 05:22 PM
15. ### Measuring effect - urgent

Hi Guys, For my thesis, I am researching the influence of colour (IV) on product attractiveness (DV). Respondents in my experiment choose one of 7...

• Replies: 8
• Views: 1,850
08-01-2016, 01:05 PM
16. ### Best Stat Question Ever?

Got this off Twitter (@galka_max) and found it interesting: If you choose an answer to this question at random, what is the chance you will get it...

• Replies: 8
• Views: 882
09-06-2017, 01:14 AM
17. ### Is survey design statistically correct?

I want to track improvements in how yoga class participants feel on various variables (e.g. energy level, sleep quality, pain felt, mental...

• Replies: 8
• Views: 1,392
04-02-2017, 10:33 AM
18. ### Joint Normal CDF

Hello I am new to this forum as well as to actuary field. I have this question: There are two random variables X_1 and X_2 following standard...

• Replies: 7
• Views: 7,545
06-20-2008, 08:13 AM
19. ### markov chain modelling

Hi guys, Got a complex question regarding markov chain modelling. I'll start off with an example. Say you own a credit card and you can only...

• Replies: 7
• Views: 4,480
08-23-2008, 09:12 PM
20. ### Expected Value of a Sample Range

The function for the expected value of a sample range is given on the following page. http://www.jmu.edu/docs/sasdoc/sashtml/qc/chapc/sect9.htm ...

• Replies: 7
• Views: 17,497
10-16-2008, 07:34 PM
21. ### (non-)parametric test dilemma

I want to compare means of 6 variables and to do correlation analysis. I did Kolmogorov-Smirnov test and it showed that 3 of them are normally...

• Replies: 7
• Views: 7,213
06-22-2009, 07:50 PM
22. ### Question: making a positive case for "no effect"

I have the results of a basic web-based marketing test. Visitors were randomly sent to one of several pages with a binary outcome of "sale" or "no...

• Replies: 7
• Views: 3,933
10-26-2009, 03:23 PM
23. ### Comparing two distributions using random drawing.

Hi all, So this is going to be a bit of a silly question: but one i've been pondering for ages. So say i've used a t-test and found two groups...

• Replies: 7
• Views: 3,930
09-18-2011, 08:11 AM
24. ### how to find the UMVUE of the location parameter under t distribution

f(x;\theta)={{\Gamma({{v+1}\over2})}\over{\Gamma({v\over2})\sqrt{\pi v}}}\Big(1+\frac{(x-\theta)^2}{v}\Big)^{-\frac{v+1}{2}} , v>=3 i have no...

• Replies: 7
• Views: 5,980
04-04-2010, 09:05 AM
25. ### How to find out the specific association of a particular age bracket to a particular

If I have a table (mXn) that contains the rows of age brackets (like 25-35 years, 35-45 years, 46-60 years) and three columns of low stress, medium...

• Replies: 7
• Views: 3,651
04-10-2010, 10:15 AM
26. ### rxc contingency table: comparison between cells?

Hello.I'm a dental student. I'm studying about how restorative methods are going to affect fracture pattern(fra.(fp)) of teeth. As a result I have a...

• Replies: 7
• Views: 5,729
06-26-2010, 04:52 AM
27. ### Significant Difference with 2 vars

Hi everyone, Is it at all possible to determine if a group of points on a scatterplot are significantly different from another group of points? ...

• Replies: 7
• Views: 3,783
06-25-2010, 11:03 AM
28. ### paired T-test or anova

Dear all just a quick simple one this time. if i had two sets of runners (in a race) for example and these two groups were linked only by the fact...

• Replies: 7
• Views: 5,598
08-23-2010, 10:53 PM
29. ### Correlation Proof

Hi guys, wondering if you could help me with a proof that I am trying to figure out. Here it is... Corr (A, B) = 0 and Corr (B, C) = 0. This...

• Replies: 7
• Views: 6,637
10-07-2010, 03:34 PM
30. ### type of study?

In a poll of 20,000 randomly selected college seniors, it was determined that 95% of them have a cell phone. What is the type of this...

• Replies: 7
• Views: 2,274
10-21-2010, 12:57 PM
31. ### Uninformative gamma prior for Poisson distribution

Hi! I want to use Poisson distribution in my research to model some waiting times and I want to set the gamma prior to its parameter. I want the...

• Replies: 7
• Views: 20,570
01-17-2011, 03:16 AM

I asked for help few days back, but probably my question was not clear that time. I have asked e-gov experts to rank some issues related to e-gov...

• Replies: 7
• Views: 2,467
01-19-2011, 05:19 AM
33. ### Normality analysis

hye guys... i need a help.. Can someone show me how to run the normality analysis... In my questionnaires, I have 4 independent variables and...

• Replies: 7
• Views: 3,169
02-09-2011, 06:58 PM
34. ### Any way to test significance?

First off, pardon my novice-level knowledge of statistics. If I make any ridiculous assumptions or whatever, this is why! So I'm doing a bit of...

• Replies: 7
• Views: 3,365
03-07-2011, 02:59 AM
35. ### Difference needed for power in fixed population.

Hi, I am designing a study to examine the difference made by implementing a new treatment strategy for a medical condition. I have become a...

• Replies: 7
• Views: 3,392
03-25-2011, 12:34 PM
36. ### Calculating Effect Size

Hi everyone I want to calculate the effect size for the national data with sample size more than ten thousand for the Independent Sample t-test and...

• Replies: 7
• Views: 4,518
05-24-2011, 11:57 PM
37. ### ANOVA vs. T-Test --> completely different results

If I compare three treatment groups with ANOVA (and Bonferroni posttesting), I get no significant difference results between groups (p>0.05)......

• Replies: 7
• Views: 18,287
06-14-2011, 12:14 AM
38. ### On what statistical significance test should I use

Hi everyone, First and foremost, my skills in statistics are quite basic so what I am about to ask may sound very stupid. That being said, here...

• Replies: 7
• Views: 2,260
08-24-2011, 01:33 PM
39. ### paired or unpaired T-Test or even some other test?

Hello there, I am trying to help out some students of medicine who are writing at their phd-thesis in germany. they have data from several...

• Replies: 7
• Views: 3,634
09-14-2011, 07:18 PM
40. ### How to Analyze this data?

OK…so I am having difficulty trying to decide exactly how best to analyze the following data. Specifically, I am trying to determine the possible...

• Replies: 7
• Views: 3,158
10-05-2011, 11:38 AM
41. ### non-significant Paired T-test, what happens next??

Hi, I'm analysing my data for my master's dissertation and I'm having problems! I have 3 "before" and "after" treatment groups (n=20 each) and...

• Replies: 7
• Views: 8,147
11-09-2011, 12:42 PM
42. ### question about null hypothesis??

here is my question: in my minor thesis, based on my theoretical framework, i have a hypothesis that stated that: "the score of group A is the same...

• Replies: 7
• Views: 2,996
01-27-2012, 04:37 AM
43. ### Convergent and Divergent Validity

Is it possible to make a multimethod-multitrait matrix of tests with different number of items? example: Test 1 consists of 5 categories with 24...

• Replies: 7
• Views: 3,601
03-06-2012, 10:30 AM
44. ### Counter-intuitive results with Bold-Brunell panel data estimator (DV-INDEX)

Hi All, I am doing Brunell-Bond panel data analysis and the results seem completely counter-intuitive. The DV is a food prices index - and so if...

• Replies: 7
• Views: 1,958
04-09-2012, 03:23 PM
45. ### Correlations between twins - who is X and wo is Y?

I have some data on twins (all fraternal) and I'm trying to see if there is any correlation between them on several measures (e.g., body...

• Replies: 7
• Views: 2,681
05-24-2012, 04:33 PM
46. ### 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: 2,384
05-28-2012, 02:04 AM
47. ### 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: 2,070
07-12-2012, 07:48 PM
48. ### 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: 2,411
07-16-2012, 03:46 PM
49. ### Mutlivariate Analysis/Using Controls

Disclaimer: I'm a student in the social sciences with *very* elementary training in quantitative methods. If I am testing the relationship...

• Replies: 7
• Views: 1,951
08-17-2012, 10:22 AM
50. ### small sample size

Hi! I want to compare 27 groups with each other, with each group consisting out of 3 or 4 samples. Can I use a one-way ANOVA or Kruskal-Wallis test...

• Replies: 7
• Views: 1,585
10-30-2012, 12:03 AM
51. ### No idea how to perform my statistical analysis...

Hello everybody! I'm new here... I'm really need help with this issue... Now I am so lost that I do have no idea how to do the stats for one of my...

• Replies: 7
• Views: 2,592
09-18-2012, 09:55 AM
52. ### What statistical procedures do I need to know to be a proficient psychologist?

Or epidemiologist? Also, Do I need to go back and study matrix algebra in detail? Thank you? What are your experiences?

• Replies: 7
• Views: 2,352
09-20-2012, 12:48 PM
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: 4,604
10-03-2012, 06:31 PM
54. ### How does observation error effect a minimal sample size for a t test?

Hello, I calculate minimal sample size to compare means of two groups (different treatment) of datapoints by a t test. For continuously...

• Replies: 7
• Views: 1,998
10-30-2012, 05:54 PM

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