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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: 18,747
10-11-2014, 12:02 PM
1. 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
2. Independent t test - small sample size - use all data points?

Hi there, I am running a small study in which both treatment (n = 7) and control groups (n= 6) have undertaken the same 48 item rating scale task...

• Replies: 1
• Views: 3,087
12-29-2011, 05:40 AM
3. [SOLVED] Option for post-hoc test after permanova for community data?

Hi there, Thank you for reading my post and hopefully someone can provide me with some help! For my master's thesis, I have used microbial...

• Replies: 3
• Views: 3,884
02-24-2016, 08:58 PM
4. reduced-form system

Hi, I am buiding a supply and demand model. I have one price and one demand equation and would like to compare the different coeffecients through...

• Replies: 2
• Views: 1,266
04-19-2015, 10:11 AM
5. grouping categorical variables for regression

I'm working with survey data dealing with reproductive health among women with HIV. I would like to explore possible factors which may contribute to...

• Replies: 0
• Views: 3,384
11-20-2010, 10:20 AM
6. t-test or Mann-Whitney test, regular research problem, need help

Hello, it looks like a most frequent research problem, but I am confused, so need help. I have 2 groups of data to compare: group 1 - people...

• Replies: 6
• Views: 12,014
10-09-2012, 06:01 AM
7. How to find minimal sample size in my case to compare means of 2 groups by t-test?

Hello, please help. I have 2 groups of people (treated with a drug and untreated). I measure percentage of green cells among particular type of...

• Replies: 4
• Views: 1,959
10-25-2012, 06:03 AM
8. 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: 2,004
10-30-2012, 05:54 PM
9. Comparing time curves for two groups in research.

Hello, I am creating time curves (experimentally) for two groups of mice (f(t) and y(t)): number of particular cells (in murine blood, per ml of...

• Replies: 3
• Views: 1,729
07-25-2014, 11:45 AM
10. normalization for detection of outliers

Hello everyone, I am working with a huge dataset and I'm trying to find outliers in each row for two subgroups of my dataset (G1 and G2)....

• Replies: 0
• Views: 3,942
10-20-2011, 08:59 AM
11. Transform data for outlier analysis?

Hey everyone, I have a data set which is log normally distributed and want to detect outliers, so far I used a threshold approach: vector...

• Replies: 10
• Views: 7,757
11-10-2011, 05:37 AM
12. Two-dimensional outlier detection

Hi all, I was wondering if you could give me some suggestions to detect two-dimensional outliers, i.e. for values depending on the variables. A...

• Replies: 1
• Views: 3,424
01-19-2012, 01:06 PM
13. Weighted values from correlation coefficients

I've been pressed to find a similar existing example of what I'm trying to do, but maybe i'm not phrasing it incorrectly. Essentially, I want to...

• Replies: 0
• Views: 313
07-19-2017, 01:35 PM
14. Low porbability from logistic regression

Hi, I am facing a situation where I have very low probabilities (ave ~0.0008) after I performed the logistic regression. My original data...

• Replies: 0
• Views: 1,538
02-09-2013, 01:38 AM
15. Rarefaction and species richness

Hi all! First of all thank you to take a look to my question, I hope this is the right subforum and I hope to explain it right! I have a...

• Replies: 0
• Views: 2,241
08-04-2013, 12:51 PM
16. Colculation Geometric Brownian Motion with deposits.

Hi all. There is a way of colculation a future standart diviation of a portfolio if you know the daily standart diviation and the mean. ...

• Replies: 1
• Views: 1,722
BGM
12-20-2014, 04:15 PM
17. determining sample size

Hello everyone, i hope that someone can help me. i'm doing an experiment at my work place. i have 4 vehicles that need to go through the same...

• Replies: 1
• Views: 1,838
11-13-2011, 05:06 PM
18. MBE, RMSE of two series of data, correlation.

I have a series of Data generated as output of a mathematical model which I already know the MBE and RMSE (real measured values and simulated ones by...

• Replies: 1
• Views: 3,286
10-10-2014, 07:10 AM
19. 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: 1,901
10-08-2009, 08:17 PM
20. 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: 1,929
10-08-2009, 08:59 PM
21. 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: 3,448
10-22-2009, 08:53 PM
22. Probability from sample size

I am working on taking a methodology class and when working on past exams I stumbled over this question. I used n=(z^2∗Var)/error^2 to obtain the...

• Replies: 0
• Views: 717
05-30-2017, 12:47 PM
23. Which test to run (pretest-posttest)

Hi there! What is the best test to use to analyze data involving a pretest and posttest given to two different treatment groups? Thanks!

• Replies: 10
• Views: 7,542
02-11-2011, 10:46 PM
24. Correlation vs ANOVA

Hi, I am trying to figure out which type of statistics to use for my research project. My knowledge of stats is limited so hopefully this makes...

• Replies: 6
• Views: 12,756
01-23-2013, 04:18 PM
25. Multiple Paired t-tests

Hi, I'm having a little bit of trouble with some research I'm doing and wondered if anyone could help. I'm looking at political decision-making....

• Replies: 3
• Views: 1,792
01-28-2014, 03:50 PM
26. testing

I am new to thread but wondering how I would go about testing inferentially a hypothesis for a research paper. It would be regarding productivity as...

• Replies: 0
• Views: 2,398
02-09-2009, 11:06 PM
27. Are there any post hoc analyses for Chi Square data?

Hi, I've got some Chi square results that I would like to analyze post hoc. Any ideas? I've got categorical data. Kind regards Brionny

• Replies: 2
• Views: 5,700
03-10-2009, 04:57 PM
28. Business location statistics.

I'm interested in researching business statistics and possible factors involved which will determine a good business location. For example, If I am...

• Replies: 0
• Views: 1,171
05-23-2015, 04:11 AM
29. Confidence Interval Question

Let Y_n be the nth order statistic of a random sample of size n from a distribution that has pdf f(x) = (3x^2)/(t^3) with 0<x<t. a) Show that P(c...

• Replies: 0
• Views: 1,759
11-14-2011, 05:49 PM
30. Limiting distribution of score variable

Prove that \frac{1}{\sqrt{n}}\left (\sum_{i=1}^{n} \frac{\partial l(X_{i};\theta )}{\partial \theta } \right...

• Replies: 3
• Views: 1,621
12-18-2011, 08:00 PM
31. Optimal tests of hypothesis

I have a question about the use of optimal tests of hypothesis in practice. Are they often used in research or in industry? I understand that UMP...

• Replies: 2
• Views: 2,177
04-28-2012, 12:06 AM
32. Ideas with paired data

Yesterday I was lucky enough to work with a statistician from another section in my division. He took me along on one of the consultations he...

• Replies: 5
• Views: 3,912
08-31-2011, 04:45 PM
33. Age Adjusted Rates

So I'm trying to make my data match, in some ways, those used by the CDC (NCHS, specifically). In particular, I need to calculate age-adjusted...

• Replies: 0
• Views: 2,002
09-13-2011, 12:28 PM
34. Error Analysis with Binned Data

Our income data comes in increments of $5,000 from$15,000 onward. The [$0 to$15,000) is one way too big of a bin. In any case, we also have...

• Replies: 0
• Views: 1,537
12-07-2012, 01:26 AM
35. 1 way Anova vs Two Way Anova -HELP needed

I suck at stats and am always confused >.< I have 24 animals. Let's say I have 3 groups of animals (A,B,C) and 8 in each group. Each group...

• Replies: 2
• Views: 3,143
01-05-2017, 09:06 AM
36. Right Sample Size

I am new to this blog and I am trying to learn statistics applied in Market Research. I have the following question: Suppose there is a population...

• Replies: 5
• Views: 5,212
11-04-2010, 12:12 PM
37. Application of Significance Testing

SAMPLE SIZE: 518 in each city QUESTION: Likeness to have Coke after dinner. Positive Response to the Question: 320 in each city ...

• Replies: 6
• Views: 5,722
12-08-2010, 12:54 AM
38. Factor Analysis vs Correspondence Analysis

I was just reading about Factor and Correspondence Analysis. I am a bit confused from the time I realised that Correspondence Analysis also uses...

• Replies: 1
• Views: 7,251
12-27-2010, 05:00 AM
39. Interpretation of Factor Analysis

I have a doubt on how to interpret the factor score output? Suppose we have data in 7 columns: Recommendation, Preference, Willingness to pay...

• Replies: 0
• Views: 3,770
01-30-2011, 08:46 AM
40. Research about stock comovements due to similar ticker symbols

Dear all, I have a small question about a small research that I wanted to do regarding stock symbol similarities and their abnormal returns. I...

• Replies: 7
• Views: 1,797
04-26-2014, 07:31 PM
41. Sports Forecasting - a million iterations

Hello, I am working on a forecasting project and would like to create a script that automates the following steps: order data by X characteristic...

• Replies: 0
• Views: 1,215
04-21-2012, 10:18 AM
42. Can a convenience sample ever be considered truly cross-sectional?

I'm having a debate over terminology with a colleague. We've done a small census survey (n<50) of residents and staff at a local out-patient clinic....

• Replies: 4
• Views: 7,507
09-18-2013, 07:50 AM
43. Choosing Kruskal–Wallis test for group comparison with unequal sizes

I'm doing a survey that first seeks to identify the motivation types of university ESL students. My advisory committee added a comparison among...

• Replies: 2
• Views: 28,080
10-31-2012, 08:10 PM
44. data not normally distributed

Hi, I had originally intended to use a mixed repeated measures anova to test my data, however unfortunately it is not normally distributed and so...

• Replies: 1
• Views: 2,118
08-04-2011, 10:19 AM
45. Testing for a change in mean in a time series

Suppose I have m observations from a time series before some specified date, and n additional observations after that date. The mean of the time...

• Replies: 1
• Views: 5,038
03-05-2011, 09:35 AM
46. Z-scores with non-normal data

Hi, I am reviewing someone's study in which they used z-scores to standardize and compare data. I see no mention of their test for normality and...

• Replies: 1
• Views: 5,187
06-06-2013, 07:46 AM
47. Tensor product

Hi in the context of a generalized additive model, can someone explain what is meant by a fully nested tensor product? In the R package mgcv,...

• Replies: 0
• Views: 1,645
06-22-2011, 01:49 AM
48. comparing models

This might be a "101" question but hey, The Ecologist" encouraged me to ask questions , lots and lots of stupid questions. So when I have two...

• Replies: 7
• Views: 2,350
12-04-2015, 10:26 PM
49. Chi sqared test or fisher exact test?

Hi, I am doind research on different treatments to a disease. I broke down the categories into different age groups, i.e. 5-10,11-15,16-20 etc. and...

• Replies: 4
• Views: 2,247
04-10-2012, 07:13 PM
50. negligible trend tests?

Greetings, I'm looking for information on how to test for a "negligible" trend. Info such as links to websites, formula/equations, and other...

• Replies: 4
• Views: 2,874
08-04-2008, 10:43 AM
51. What Measure - Nominal, Ordinal, Scale? SPSS

I'm using SPSS to enter data and I just want to make sure I picked the appropriate measure for each variable State - Nominal Population - Scale...

• Replies: 1
• Views: 14,449
12-14-2010, 07:22 PM
52. Principle Components, Canonical Variate Analysis and Win-DAS

I'm trying to follow some analysis procedures as presented in an applied microbilogy paper. The authors did a principle components analysis (PCA)...

• Replies: 0
• Views: 1,338
10-07-2013, 03:17 PM
53. Questions about approach

Hi, I am working with a large data set with all categorical variables except for age, which I will want to group in to age bands. I think I am...

• Replies: 2
• Views: 2,335
03-29-2011, 09:23 PM
54. DOE for Logistic Regression

Hello- Does anyone have any references for DOE (especially multivariate testing / Taguchi) for binary response variables (analyzing with Logistic...

• Replies: 5
• Views: 4,221
08-28-2008, 11:18 AM
55. Percent From The Critical Value

Afternoon, Here is one I haven't experienced before and haven't seen discussed: I have a series of goodness-of-fit tests using chi-square a few...

• Replies: 0
• Views: 1,104
06-20-2016, 01:46 PM
56. URGENT: Two-Way Anova or Regression

Hi, I would really appreciate some help with this. I am looking to see if employees' organisational history (such as voluntary/involuntary turnover)...

• Replies: 3
• Views: 1,116
01-24-2014, 01:47 PM
57. Variation of Mantel test?

Hello. I am new to this forum but it looks like it will be a great reference! For my thesis I used Mantel tests to compare non-parametric...

• Replies: 1
• Views: 1,225
04-02-2014, 12:27 AM
58. Cluster analysis

Hi all! I am new here, and I need some help. I have done some cluster analysis (K-means), and got four groups, two of which are "high" and "low"....

• Replies: 5
• Views: 2,107
11-12-2011, 10:34 AM

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