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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: 18,689
10-11-2014, 12:02 PM
1. ### Variance estimation

A simple question we have a random sample n=2 with X, Y drawn from a normal distribution N~(0, \sigma^2). Is V=\frac{X^2}{2}+\frac{Y^2}{2} a...

• Replies: 21
• Views: 6,451
11-01-2010, 06:42 AM
2. ### Linear estimator of mean

Problem is solved! :)

• Replies: 0
• Views: 1,849
11-03-2010, 05:19 AM
3. ### 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: 4,617
11-28-2010, 06:07 AM
4. ### Algebra, two-sample t-statistic, variance

• Replies: 20
• Views: 5,765
08-13-2012, 12:31 AM
5. ### Gpower

I'm wanting to run a study where I record motor evoked potentials evoked from a group of participants they view images of people performing reach and...

• Replies: 2
• Views: 5,093
01-11-2011, 08:28 AM
6. ### bridge estimation in linear regression

So the bridge estimates, \beta (which is a vector of \beta_1,...,\beta_p), minimize \sum_{i=1}^n (y_i - x_i^T\beta)^2 +...

• Replies: 0
• Views: 2,327
11-25-2010, 11:53 PM
7. ### number of distinct samples in sampling with replacement

If I have a set (X1, X2,X3) and I want to re-sample them with replacement, the possible combinations of the samples are (the order doesn't matter):...

• Replies: 0
• Views: 3,602
02-01-2011, 06:58 PM
8. ### 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: 4,835
03-29-2011, 09:09 PM
9. ### nonparametric estimate the distribution with a histogram only

Suppose X1,.., Xn ~iid F with mean mu_F The data is summarized in a histogram and that is all I have. I don't have the individual Xi (i = 1,...,n)....

• Replies: 3
• Views: 3,072
BGM
03-24-2011, 11:47 PM
10. ### bias of the coefficient of variation

Is the coefficient of variation biased? How would you compute the bias of CV? Can I write E(sigma_hat/|mu_hat|) = E(sigma_hat)E(1/|mu_hat|)+ ...

• Replies: 4
• Views: 5,666
03-30-2011, 02:38 PM
11. ### EM Algorithm for Gaussian Mixture model fitting data with missing values

I have an EM function that will take regular data with no missing values, and compute means, standard deviations, and probabilities of components of...

• Replies: 1
• Views: 4,369
04-12-2011, 11:26 AM
12. ### about random walk Metropolis algorithm

Our model is: Y is distributed from a Negative binomial(r,p) where log(p/1-p)=xb. The prior of b is a multivariate normal(mu0,...

• Replies: 3
• Views: 2,187
01-06-2013, 07:50 PM
13. ### Which Tests?

Hello! I am considering a study I'll note below, but have limited statistical experience. Accordingly I am seeking insights on which tests are...

• Replies: 2
• Views: 2,254
08-03-2014, 10:56 PM
14. ### might be a stupid question...

I am comparing 2 groups (matched sample) with t-tests and am noticing that there is no significant difference. However the st. deviations of each...

• Replies: 2
• Views: 3,724
03-16-2009, 11:07 AM
15. ### t-tests or mann-whitney??

Hello, I have a n=12 sample (and a matched-sample of 12)... I was planning on using t-tests, but now reconsidering it. Would it be correct to use...

• Replies: 2
• Views: 8,537
05-03-2009, 06:41 PM
16. ### Looking for appropriate non-parametric test for 5 dependent group & small sample size

What is the most appropriate parametric test for repeated observations for multiple dependent groups.

• Replies: 1
• Views: 2,225
01-29-2017, 12:56 AM
17. ### Difference between two independent proportions

Hello, I am not a statistician, however, for my latest small research, I would like to test whether there is a difference between two independent...

• Replies: 4
• Views: 4,157
03-03-2017, 01:48 PM
18. ### Survey Analysis

Hey Guy's I really need your help. I am not a statistician. I have to analyze surveys that have 6 observations (people) and 20 factors (food...

• Replies: 8
• Views: 2,261
01-30-2012, 12:20 PM
19. ### Confidence interval and P-value

Hello Guy’s thanks for your help in advance I am working on a research paper. I have large set of data (50,000) which allow me to use normal...

• Replies: 3
• Views: 2,312
02-08-2012, 11:48 AM
20. ### MDS with confusion matrix

Hi, I want to run a MDS from some data of close set identification. Therefore, I have a 12X12 confusion matrix and I need to transform it to a...

• Replies: 0
• Views: 2,800
06-23-2009, 07:12 PM
21. ### Kruskal-Wallis or Poisson regression for parasite count data?

Trying to figure out how best to carry out this analysis... So essentially I have four different species of Deer mice, infected with a high, medium,...

• Replies: 4
• Views: 1,514
10-27-2015, 05:28 PM
22. ### Sampling Method? Too many schools to sample

I am part of a research team looking at the outcomes of a homework help program and would like to make a few suggestions of how to generate data. ...

• Replies: 0
• Views: 2,186
04-24-2009, 11:07 AM
23. ### Which basic stat test to use?

I have done a lot of linear modeling for my thesis, however one of the unsolved stat problems I have should be a pretty basic issue. I am testing to...

• Replies: 1
• Views: 1,213
04-01-2014, 04:17 AM
24. ### May anyone please tell me what does this output express?

image hosting 5mb

• Replies: 0
• Views: 1,147
09-01-2015, 06:08 PM
25. ### Missing values with Row and Column Totals

Hello everyone, I'm working with government panel data (yearly data of manufacturing industry (row) by continent (column)) that has a lot (about...

• Replies: 0
• Views: 1,912
03-23-2011, 12:41 PM
26. ### What should i do next?

Hi all, I want to see the effect of gender changes depending on the race of student when they have drunk driving behaviors. There is an...

• Replies: 0
• Views: 1,064
10-26-2013, 10:13 PM
27. ### Question about sample size and margin of error

I am trying to determine if my dataset sample size is large enough to be statistically significant. I'm using a 95% confidence interval. However,...

• Replies: 3
• Views: 1,391
12-06-2013, 02:46 AM
28. ### Bayesian approach to comparing parameters of two distributions

This is my first post here, and I'm hoping that someone can help me with a stats problem. I don't have much formal training, but I'll do my best to...

• Replies: 4
• Views: 2,977
05-09-2012, 02:20 PM
29. ### survey weighting and calculation of confidence intervals for proportions

Hi all I'm working with data from a one-off cross-sectional random sample survey that has weighting that can be applied to make it representative...

• Replies: 0
• Views: 3,738
08-07-2012, 04:20 PM
30. ### Comparing Mean and Median

Hello people. I'm currently doing a research on household income and expenditure in my country, and I'm faced with some problems: 1. Are mean and...

• Replies: 2
• Views: 2,190
08-24-2013, 05:52 PM
31. ### How do I calculate the Sample Size for this type of Survey?

Hi all, I need to calculate the sample size for a survey I will be undertaking soon. The target population will be the clients of 8 hotels,...

• Replies: 0
• Views: 1,009
03-15-2013, 11:53 PM
32. ### markov chains- estimation

Hello all, my task is to estimate parametres of markov chain model basing on real economic data. Does anyone have any idea what sort of data would...

• Replies: 1
• Views: 2,639
01-12-2008, 10:19 AM
33. ### T-test appropriate?

Hello all, I have a big dataset which I divided into different periods (years) and focused on one group. I calculated the means for the different...

• Replies: 3
• Views: 2,426
04-28-2011, 06:33 AM
34. ### sample and gander

Hi all, I have a newbie question I'm doing a small research about the prevalence of smoking in diabetic patient. My sample size is 300. However,...

• Replies: 0
• Views: 1,697
10-02-2013, 12:54 AM
35. ### Converting 1 Distribution to Another

I have a set of values ranging from .01 to 918 with n = 7368. About 3000 values are below 1 and about 150 values are greater than 100. The mean and...

• Replies: 5
• Views: 4,506
03-26-2010, 12:50 PM
36. ### Statistical Theories, Methods, and Fields applying to Educational Assessment

I'm interested in doing research in education and statistic. Particulary with student assessment and students. However, I know this is very broad and...

• Replies: 4
• Views: 1,923
08-17-2012, 04:04 PM
37. ### Type of Stats

I am new at this - I have to design - on paper - a test to teach reading. I want to do a Pre-Test and Post-Test - compare the differences. I also...

• Replies: 1
• Views: 1,866
12-17-2013, 05:37 PM
38. ### Paired t- test experiment

Hello, I have a sample 20 super market stores of a specific chain (who has in total 100 super market stores). In 1st of July there was an increase...

• Replies: 0
• Views: 2,920
05-14-2011, 05:34 AM
39. ### Question about theta range in MA(1) processes

Hello, According to forecasting textbooks (e.g. Diebold, Makridakis etc) the theta coefficient in an MA(1) model should be between -1 and 1...

• Replies: 1
• Views: 4,004
BGM
09-08-2011, 08:45 AM
40. ### Question about phi range in AR(1) process

Hello, Makridakis Forecasting text book says that phi should be restricted to -1<phi<1. I thought that this restriction should exist only if we...

• Replies: 4
• Views: 5,158
09-08-2011, 02:08 PM
41. ### Standard Errors of Exponential Smoothing Coefficients

Hello, I use SAS ETS to estimate a single exponential smoohting model. When i select the optimize option for the estimation of the smoothing...

• Replies: 0
• Views: 2,060
09-12-2011, 03:25 AM
42. ### Yule Walker - AR(1) - Covariance Forumla

Hello, I have the AR(1) process: Yt=phi*Yt-1 + et According to text books we ,ultiply by Yt-k, so we have: Yt*Yt-k=phi*Yt-1*Yt-k+et*Yt-k and...

• Replies: 1
• Views: 4,255
10-01-2011, 11:22 AM
43. ### Unobserver Component Models for Forecasting vs ARIMA and Expoential Smoothing

Hello, I read in textbooks and in forecasting software manuals that Unobserverd Components Models have the flexibility and are as powerfull as...

• Replies: 0
• Views: 3,066
10-15-2011, 12:00 PM
44. ### 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: 4,968
11-06-2011, 06:24 PM
45. ### Cointegration and Correlation

Hello, Based on real data (e.g. spot and futures prices of an index) if two series are correlated in the long run (e.g. strong positive...

• Replies: 0
• Views: 2,062
11-08-2011, 07:02 AM
46. ### Calculation of Autocorrelation

Hello, I have a data set of which i calcualte the autocorrelation at lag 1 in SAS ETS (Proc Arima) and SPSS. Then i try to calculate the...

• Replies: 2
• Views: 5,159
11-18-2011, 09:36 AM
47. ### Dickey Fuller Test

I am studying the Dickey Fuller test. The book of reference is Introductory Econometrics for Finance by C. Brooks. I firstly consider the zero mean...

• Replies: 1
• Views: 3,128
11-25-2011, 01:49 AM
48. ### Decision Tree with Binary Target

Hello, I have a dataset with a number of inouts and a binary target. I want to build a decision tree model. SAS states that the predictions can be...

• Replies: 1
• Views: 1,269
09-24-2012, 09:56 AM
49. ### Target Layer Activation Function of a Neural Netwrok with Ordinal Target (3 events)

Hello, I have a neural network with an input layer, two hidden layer and one target layer. The target is binary (1,0). The activation function is...

• Replies: 0
• Views: 1,300
10-22-2012, 04:28 AM
50. ### how to calculate Factor Scores?

Hello folks, I need to know how to calculate factor score in Principal Component Analysis. I know in SPSS, it gives option of calculating it using...

• Replies: 2
• Views: 11,744
11-23-2010, 12:28 PM
51. ### probability inequality

Let X be a random variable such that |X|<=C (bounded). Let f be an even, non decreasing function over the positive values of x. Prove that: /f(C)...

• Replies: 4
• Views: 2,601
02-06-2010, 05:53 PM
52. ### Comparison quantity with mean values and measurement uncertainty

Hi !! I need help in a problem. I measured a quantity Q from the area A of a peak (normally distributed) divide by two factors. The uncertainty...

• Replies: 0
• Views: 1,494
08-30-2014, 10:47 AM
53. ### Need help analyzing data in SPSS

Hello everybody :) We conducted a simple experiment, our hypothesis was that negative biometeorological forecast induces nocebo effect, especially...

• Replies: 14
• Views: 2,519
04-26-2013, 08:59 PM
54. ### Is MANOVA the correct way?

Hi all, In my research, I have values for 7 (+ 1 for reference) devices that measured the (walking) steps at the same time (so that I would be...

• Replies: 0
• Views: 1,252
05-17-2014, 05:25 AM
55. ### How should I explain this results?

The hypothesis is: the willing-to-pay is higher when people see print ad with testimonial. So there are four print ads 1. 1 cola ad with...

• Replies: 4
• Views: 1,584
11-14-2015, 01:34 PM
56. ### How should I further analyse this result?

• Replies: 4
• Views: 2,050
12-04-2015, 04:05 AM
57. ### How should I run an interaction test to find out the main effect of ad type?

Hello everyone, I designed an experiment. There are two types of advertisement, type 1 and type 2. 50% of my participants looked at the type 1 and...

• Replies: 1
• Views: 1,112
01-21-2016, 04:36 AM

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