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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: 18,729
10-11-2014, 12:02 PM
1. ### How to compute significance here? (And why?)

Hello, method test_set_size correct accuracy A 898 188 0.209 A+ 898 210 0.234 A++ ...

• Replies: 0
• Views: 3,258
07-28-2009, 06:02 AM
2. ### return series

why does taking a log make a return series continous? ln(r(t)/r(t-1))

• Replies: 0
• Views: 1,838
07-28-2009, 08:22 AM
3. ### I have no idea where to start!!

I need to analyse data for research--- There are 3 outcomes (1,2,3) and two companies (a,b) with 3 departments each (a1,a2,a3 and 1b,2b,3b). I...

• Replies: 2
• Views: 2,430
08-05-2009, 05:36 PM
4. ### Gumbel Copula

Does anybody have some code or a paper to show how to simulate n dimensional Gumbel copula ?

• Replies: 0
• Views: 2,401
08-12-2009, 02:55 PM
5. ### Research Question

Hey Everyone hopefully you can help me. My last hope ;-). For a Stat's and Research Exam (on Monday) I need to answer the following questions: Draw...

• Replies: 0
• Views: 2,468
08-14-2009, 05:28 AM
6. ### comparing means\unequal(small) size group

Hi, I am about to use student t test to compare the mean of two independent groups. The first group sample size is 4 and another one is 24. Can I...

• Replies: 4
• Views: 26,356
08-18-2009, 12:00 AM
7. ### Fisher information matrix

Hello everybody, I read here that the Fisher information matrix was the inverse of covariance matrix. How can I show that ? My definition of...

• Replies: 0
• Views: 4,260
08-20-2009, 09:01 AM
8. ### Multiple Comparison Correction - Help needed !

I know the concept that one should have statistical correction if multiple comparison are made between means. Such as the well-known bonferroni...

• Replies: 1
• Views: 4,033
08-20-2009, 09:42 AM
9. ### bounds of beta distributions

I'd like to estimate the lower and upper bounds of a general beta distribution, using 5 and 95 percentiles. I already know how to estimate the mean...

• Replies: 0
• Views: 2,148
08-20-2009, 11:20 AM
10. ### Violation of sphericity...

If you seem to be violating the assumption of sphericity when undertaking several separate one way repeated-measures ANOVAs and therefore have to...

• Replies: 0
• Views: 3,834
08-20-2009, 03:26 PM

I have just obtained the output for a one way repeated measures ANOVA and have read that it is useful to report the size of the effect using omega...

• Replies: 0
• Views: 5,738
08-20-2009, 03:28 PM
12. ### What N to record for regression table?

Is it the outcome variable (dependent variable) N that I report in a regression table?

• Replies: 0
• Views: 1,912
08-20-2009, 07:08 PM
13. ### 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: 4,669
08-21-2009, 01:41 PM
14. ### Binomial Test that does not assume indepence? (using a repeated measures design)

Hi, I am looking for a way to analyze data for the following experiment: subjects were presented with two separate acoustic signals at the same...

• Replies: 1
• Views: 2,679
08-23-2009, 01:08 PM
15. ### Do I have a problem with simultaneity here??

Hi, I am modelling the demand for imported rice for a sample of countries. The price of imports, one of the explanatory variables, is assumed to...

• Replies: 0
• Views: 3,308
08-29-2009, 07:06 AM
16. ### mathematics (is it a differential equation?)

Hi there, Well I know I'll sound rusty in mathematics but here I go: Let a vector b=. I know the derivatives dQ/db0 and dQ/db1. I am...

• Replies: 2
• Views: 3,275
08-30-2009, 03:33 PM
17. ### p =.046 significant?

If I get a probability value of .046 is this considered significant given significance level of .05?

• Replies: 5
• Views: 8,017
09-02-2009, 10:46 AM
18. ### Why no international statistical testing?

I am wondering why it's generally not done to conduct a statistical testing comparing prevalence rate between two different countries even they have...

• Replies: 3
• Views: 2,395
09-06-2009, 08:51 PM
19. ### Trouble with a dichotomous decision study

Any help appreciated: Have a study with video clips and a Yes / No answer. There is a correct answer. There are ~20 (but this can be changed) clips...

• Replies: 0
• Views: 2,758
09-09-2009, 11:10 AM
20. ### which test to use?

Hello everyone, Im a bit stuck as to which test i should be using for my analysis. i have collected the reaction times of 35 participants. There...

• Replies: 3
• Views: 1,900
09-15-2009, 07:33 AM
21. ### 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: 4,654
09-18-2009, 12:06 AM
22. ### Fisher's z transformation in path analysis

Hi guys. I am a psychology honours student doing my thesis by producing a path analysis that I ran with two different samples - one with a younger...

• Replies: 0
• Views: 3,396
09-21-2009, 09:14 PM
23. ### Tricky(?) sampling problem

Hello all! I have a survey data set consisting of interview answers of different people. The people have been sampled with simple random sampling....

• Replies: 3
• Views: 3,669
09-27-2009, 02:33 PM
24. ### Levene's Test - Large F Value

Hi all, My F Statistic from Levene's Test is very high. The significance is .000. My question is: should an independent T-test even be used...

• Replies: 1
• Views: 7,543
10-02-2009, 11:02 AM
25. ### multivariate statistics in Izhikevich model

I have a simple cortical brain simulation model that has an output parameter and various input parameters. The output is the correlation coefficient...

• Replies: 0
• Views: 1,899
10-08-2009, 08:17 PM
26. ### Is this a good idea?

I have a simple cortical brain simulation model that has an output parameter and various input parameters. The output is the correlation coefficient...

• Replies: 0
• Views: 1,928
10-08-2009, 08:59 PM
27. ### Correlation versus Regression

Hi, I am trying to find an impact of some factors on overall satisfaction. Could you please advice me whether correlation or regression is better?...

• Replies: 1
• Views: 2,452
10-09-2009, 07:34 AM
28. ### Estimating initial level after the treatment!

Hi, Say I wanted to examine the effect of some treatment on a hormone level but I could not measure the pre-treatment level. Example, person runs...

• Replies: 3
• Views: 2,636
10-09-2009, 11:46 AM
29. ### Process averages as data points in factorial ANOVA

(Reposting here, original posted in the "Statistical Consulting" forum) Hello all! Electrical engineer here, currently doing research in...

• Replies: 1
• Views: 2,221
10-13-2009, 09:29 PM
30. ### T test

Experimental design 3 virus types x 3 exposure concentrations x 2 replicates of 15 fish How can I use the T test to determine if my replicates...

• Replies: 1
• Views: 1,946
10-13-2009, 10:12 PM
31. ### 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: 4,897
10-14-2009, 12:43 PM
32. ### I'm Confused, simple question...

Hello all. I was reading a friend's dissertation and came across something that left me a bit perplexed. In his study, he stated that there...

• Replies: 3
• Views: 2,809
10-15-2009, 03:56 PM
33. ### compare unequal-size groups, Likert scale, t-test

Hello! I have 28 students questionnaires to analyse, these 28 students distributed into 3 groups. in the experiment the 3 groups were put in the...

• Replies: 1
• Views: 7,621
10-19-2009, 01:17 AM
34. ### Interactions in R and posthocs (lmer model)

Hello there, here's a question about interactions. Let's just say you have the variables Diagnosis with two levels LI (language impaired) and N...

• Replies: 1
• Views: 6,234
10-20-2009, 10:51 PM
35. ### logistic regression

Hi there, In the case of logistic regression with one covariate we have our binary data (vector y),and the covariate vector x, which can be used...

• Replies: 0
• Views: 1,996
10-22-2009, 10:37 AM
36. ### What is a monte carlo simulation?

I am doing some research and think I am doing a monte carlo simulation. Could some body please tell me what that is? If someone could also tell me...

• Replies: 1
• Views: 3,444
10-22-2009, 08:53 PM
37. ### Methodology for building a model based on available time series

Hi everyone For my Msc research I am trying to estimate a bus demand model based on anuall historical data of demand itself and other explanatory...

• Replies: 2
• Views: 2,161
10-26-2009, 12:47 PM
38. ### 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
39. ### bootstrap and non-stationarity

Dear all, Is it true to say: If a time series X(t) does not satisfy the strict stationarity condition: P(X(t+1), X(t+2), ... , X(t+T)) =/=...

• Replies: 0
• Views: 2,550
11-03-2009, 02:06 PM
40. ### Certain sample size needed for HLM?

I have a data set of test scores and memory scores of 111 students, nested in 12 different classroom. 6 classrooms are from high income areas and 6...

• Replies: 3
• Views: 17,342
11-04-2009, 10:14 AM
41. ### HELP: Put in practice statistical test methodologies

Hi to everyone. I'm doing a research work about forecast and I found two papers that are very helpful. What I need is to use the methodologies...

• Replies: 0
• Views: 2,339
11-06-2009, 04:58 PM
42. ### Help for Web Log stats on blog site...

Hello, I have been asked to run an on-going, weekly statistics rankings of topics on a website (blogs). Each blog author lists 'topics', selected...

• Replies: 1
• Views: 2,369
11-10-2009, 03:01 PM
43. ### Why does a model with an interaction has to include the interaction main effects?

:wave: Hello fellow stats talkers, If we are only interested in an interaction, I was wondering why a model with a significant interaction also has...

• Replies: 1
• Views: 6,233
11-11-2009, 08:52 AM
44. ### Nonparametric regression

Hi guys, can someone recommend a good source to learn about kernel regression or spline smoothing and perhaps how to compare two plots to each other?

• Replies: 2
• Views: 3,037
11-17-2009, 01:06 AM

My manager wants me to do a research about advance purchase day vs. fare. however it involves too many categories, and we have billions of tickets...

• Replies: 0
• Views: 2,228
11-19-2009, 12:05 AM
46. ### Rolling regressions

Hi everybody, I was wondering if any of you have any experience with rolling regressions and how to calculate significance when using them. I...

• Replies: 0
• Views: 4,227
11-20-2009, 10:51 AM
47. ### Time Series

Hi everyone, I've been reading some papers that talk about fractality (hurst exponent) in physiological time series (ekg, eeg, gait, etc.). I was...

• Replies: 0
• Views: 3,210
11-23-2009, 03:32 AM
48. ### attributes of individuals in discrete choice tasks

Hello stat talkers, :wave: I'm currently working on a marketing (discrete choice) project concerning brand choice and I stumbled upon some questions...

• Replies: 3
• Views: 3,431
11-23-2009, 04:23 AM
49. ### Help with bimodal distribution

I have a bimodal distribution which I think is made up of 2 normal distributions. How can I tell the 2 distributions apart? In other words I would...

• Replies: 0
• Views: 4,158
11-26-2009, 09:03 AM
50. ### Regression on Binned data

Hi, Can I carry out linear regression reliably with binned data. IE. data on cases falling into a series of ranges over time. I can imagine...

• Replies: 0
• Views: 3,609
Cox
11-30-2009, 09:38 AM
51. ### Relationship between foods consumed and diseases developed

What kind of data can we collect to find out the relationship between foods consumed and diseases developed? If a patient says he is a vegetarian...

• Replies: 0
• Views: 2,240
12-01-2009, 11:55 PM
52. ### Analysis of 5 point Likert Scale Data

I am working on analysis of a survey conducted with a 5 point likert agreement scale. I need to explain why 70&#37; agreement (combined agreed and...

• Replies: 1
• Views: 12,372
12-15-2009, 08:47 PM
53. ### 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: 4,996
12-18-2009, 03:14 AM
54. ### Measuring Neural Network Performance

Hi all, I have a set of matrix where the last column is the RESPONSE VECTOR. I have performed a backprop NN (neural network) in order to...

• Replies: 4
• Views: 5,239
12-21-2009, 04:14 PM
55. ### Simple regression

Hi, I am having a problem and I know a way to solve but don't know how to statistically implement it. I'm trying to summarize the problem in a...

• Replies: 4
• Views: 2,822
12-25-2009, 09:18 PM
56. ### Reading Research - ANCOVA?

I have a class (n=30).Using a variety of test I split them into stronger readers - SR (16), weaker readers WR (14) - Quasi-experimental I chose a...

• Replies: 0
• Views: 2,908
12-29-2009, 09:05 AM
57. ### By-item random intercepts--to include or not to include?

We're hoping someone can shed light on this one... :) In experiments involving human subjects, samples are taken from the population. The same can...

• Replies: 1
• Views: 2,917
01-01-2010, 02:46 PM

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