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# Forum: Statistics

Statistics course and homework discussion. Elementary statistics.

1. ### Sticky: Forum Guidelines: Smart posting behavior pays off

Welcome to talkstats.com, the place for statistics help. This is a guideline for people who want to ask a question on this forum and value a...

• Replies: 1
• Views: 196,968
07-16-2014, 11:01 AM
2. ### Sticky: We only provide homework help to those who show effort

Welcome to Talk Stats Forum. In order to keep homework help effective and efficient, we request all members to abide by these guidelines: 1)...

• Replies: 0
• Views: 66,862
09-30-2005, 09:44 AM
1. ### Question about Bayesian statistical test and p vlaue

Just started to learn about Bayesian inference. I have no problem with Bayesian Theorem. But it's very confusing comming to Bayesian inference. Here...

• Replies: 0
• Views: 1,256
07-01-2013, 10:02 PM
2. ### Help with creating regression model for some data I have collected

before I start I apologise for not using all the correct terminology(some of it eludes me at this stage)... So i have collected a variety of data...

• Replies: 3
• Views: 1,431
07-01-2013, 09:56 PM
3. ### Calculate expected value and variance.

Xi are IID following geometric distrition (i=1..n). Y=1/(a+Sum(Xi)), where a is known constant. How to calculate E and Var(Y). Many thanks. ...

• Replies: 6
• Views: 1,547
07-01-2013, 05:59 PM
4. ### How to do this hypothesis test about Bernoulli process

Hi, I'm stuck with this question about Bernoulli process. Could someone give me some clue? First define experiment A as Repeat a Bernoulli...

• Replies: 7
• Views: 2,360
06-30-2013, 06:54 PM
5. ### Create Multivariate Linear Model in Matrix Notation

Two spider species (A and B) areto be compared to see eats flies quickest. One hundred flies are released into a cage, and one spider of each...

• Replies: 7
• Views: 1,738
06-30-2013, 04:39 PM
6. ### How to determine what IV is the best predictor of DV? Advice appreciated

I work in real estate. I am trying to determine what quantitative characteristic is the most reliable indicator of sale price. In other words, in...

• Replies: 1
• Views: 1,069
06-30-2013, 03:04 PM
7. ### Post-hoc vs sensitivity vs sub-group vs meta-regression analyses

Hello, newbie here! Firstly - apologies if this is not the forum to be asking really basic stats questions, but I'm struggling with a few bits of...

• Replies: 0
• Views: 1,659
06-30-2013, 03:08 AM
8. ### Best book on mathematical statistics

Hi Please advice me a good book on mathematical statistics.I want it to be oriented in math students or engineering level. Best Regards

• Replies: 2
• Views: 7,846
06-29-2013, 10:45 PM
9. ### Multivariate Regression - Errors & Design Matrix [Theory]

Suppose you have an experiment with the design matrix X' = 2x4 Matrix Is it true that e^1 + 2e^2 + e^4 = 0 Show your calculations. My...

• Replies: 2
• Views: 1,624
06-29-2013, 10:44 PM
10. ### How does test difficulty affect correlations?

Hi, Can anyone help me here, I know that if you have one difficult test/task and one less difficult that the correlation between them would be...

• Replies: 1
• Views: 1,343
06-29-2013, 01:31 AM
11. ### Multivariate Multiple Regression - multivariate tests

Hi guys, I need to really understand Wilks' Lambda, Roy's greatest root and other multivariate tests but IN THE CONTEXT OF MULTIVARIATE MULTIPLE...

• Replies: 0
• Views: 1,218
06-29-2013, 01:25 AM
12. ### How to rescale variables measured on different scales to be the same?

This is a situation when z-transformation will not help. Specifically -- I have longitudinal data and my DV of interest is measured on a certain...

• Replies: 2
• Views: 1,741
sem
06-28-2013, 03:19 PM
13. ### Regression analysis: selecting TREND or FORECAST formula

Hello, I am doing a regression analysis on average price increases from a PPI table, and my goal is to project a 2013 value using the average...

• Replies: 1
• Views: 2,134
06-28-2013, 09:39 AM
14. ### Need help to compute a stat or two

I wish to augment some software I've been developing with some statistical output, but I haven't been able to work out how to do it. Here's an...

• Replies: 0
• Views: 1,096
SPB
06-27-2013, 11:05 PM
15. ### Regression not correct model?

Hello everyone. I would like to develop a model that would "predict" future pre-payment rates of a given pool of loans. The question I have is, if...

• Replies: 3
• Views: 1,273
06-27-2013, 05:38 PM
16. ### Dummy variable trap help

Hey guys, I have 3 groups of dummy variables (country, year, industry). I know that normally one dummy is supposed to be dropped to avoid the trap,...

• Replies: 0
• Views: 1,718
06-27-2013, 05:09 PM
17. ### Which test to be used?

Hi everybody, I need to analyze possible differences in the invertebrates populations living in 3 different environmental treatments (3 plus 3...

• Replies: 0
• Views: 1,235
06-27-2013, 04:15 PM
18. ### Intresting In Statistics

Hi , I hope you all of you fine if any wanna intrested or want to work together, or publishing the paper he can contact with me, I will help all of...

• Replies: 0
• Views: 1,178
06-27-2013, 12:39 PM
19. ### Recommend a statistics book for data analysis (SPSS/sigmastas/excel/metlab etc)

Hello, Is there a book which I can read which helps me speed up my knowledge on statistics analysis using the software? I have come upon:...

• Replies: 5
• Views: 4,435
06-27-2013, 06:35 AM
20. ### Testing data to determine proficiency.

Hi, I have been giving a work project and I believe that I need to use t-tests to get to my results, but don't know what results I need to get to...

• Replies: 0
• Views: 1,528
06-26-2013, 05:41 PM
21. ### combining correlations/regressions

Currently working on a project testing several variables related to battery lifespan. With the 20 or so variables I have tested, I have determined...

• Replies: 0
• Views: 1,119
tbb
06-26-2013, 02:26 PM
22. ### Correlation and range

Background: I am working on this project that examines the relationship between battery life and several variables. However my specific question...

• Replies: 1
• Views: 1,102
06-26-2013, 12:13 PM
23. ### Relevant statistical method to analyze data

I want to compare two management accounting practices (ABC and TDABC) in order to find out which one is more effective. Effectiveness will be...

• Replies: 2
• Views: 1,554
06-26-2013, 11:59 AM
24. ### CI Question?

What do the size of the boxes in the 95% CI mean? Is it just the weight of the sample? ...

• Replies: 5
• Views: 1,537
06-26-2013, 09:39 AM
25. ### hypothesis testing and CI for proportions

Hello I am confused, when making inference on one proportion, using the Z approximation, we put \hat{p} under the square root (the standard...

• Replies: 1
• Views: 924
06-25-2013, 10:03 PM
26. ### Calculating Representative Sample Size - Appropriate?

Hello, In my organization, I work alot with surveying. Typically, when I need to know what the appropriate sample size would be, given a known...

• Replies: 0
• Views: 2,069
06-25-2013, 09:56 PM
27. ### Probability of values lieing between a minimum and maximum value

Hello, I'm hoping for some help on the following issue. Given a population of N=400. Each element represents the length of a part that should lie...

• Replies: 3
• Views: 2,215
maq
06-25-2013, 07:58 AM
28. ### Standardizing 2 data points

Hi, I was wondering if you have a mean and SD for 2 data points (i.e., debt and salary) is it possible/wise/statistically sound to combine these...

• Replies: 0
• Views: 1,520
06-25-2013, 05:54 AM
29. ### Variance Ratio

Hello all I have a question regarding hypothesis testing. From a population X we take a sample of size 10. The sample variance is 16. From a...

• Replies: 2
• Views: 1,197
06-25-2013, 04:27 AM
30. ### Determining which sample is larger by looking at...

Group---R-----R2-----R2adj 1-------0.79--0.62---.34 2-------0.83--0.69---.68 Is it possible to say that one of these groups has a larger sample?

• Replies: 0
• Views: 958
06-25-2013, 03:43 AM
31. ### H0 is true, then MSb/MSw=1 Why?

If the null is true, i.e. no effect of the independent variable on the dependent variable, theoretically the ratio between MSb and MSw should be...

• Replies: 0
• Views: 1,838
06-25-2013, 03:26 AM
32. ### Factor Extraction in SPSS

What are the reasons I am unable to complete a factor extraction in SPSS using maximum liklihood. When I attempt to perform it, it says "Attempted to...

• Replies: 1
• Views: 1,739
06-24-2013, 11:59 PM
33. ### Is it possible to use paired t-test to compare changes in multiple subjects?

I have designed 5 different controllers for a biomechanical model, and I quantify how each controller performs by applying each to a standard set of...

• Replies: 0
• Views: 1,988
06-24-2013, 08:31 PM
34. ### non-central chi-square distribution.

If X_i is distributed as normal with mean \mu and variance-covariance matrix D,where D is the diagonal matrix, then show that X^TD^{-1}D is...

• Replies: 3
• Views: 1,739
BGM
06-24-2013, 10:47 AM
35. ### Trend Analysis on Positive and Negative Data by Department

I work for a company where I am developing a trend analysis tool to analyze various data. My specialty is in the area of Access...

• Replies: 0
• Views: 2,489
06-24-2013, 08:42 AM
36. ### Geometric mean of normally distributed independent random variables

Hi all, I have a large set of identical normally distributed random variables, all positive and independent, with the same known Mu and Sigma for...

• Replies: 5
• Views: 8,705
06-24-2013, 06:53 AM
37. ### What will be the transformation and Jacobian of transformation for the following case

Let X_i\sim N(\mu_i,\sigma^2) ; where show that \bar X and (X_i-\bar X) are independent. If all X_i had same mean \mu then we transform the...

• Replies: 1
• Views: 1,949
BGM
06-23-2013, 09:47 PM
38. ### [response set analysis] respondents unaware of negative formulated items

Hi I’m wondering what to do when negative items does not break response set. In other words, it remain unclear if respondent was where of the...

• Replies: 0
• Views: 1,842
06-23-2013, 10:58 AM
39. ### Checking the Independence.

Let X_i\sim N(\mu,\sigma^2) ; where Z_i\sim N(0,1) ; where Proof that \frac{(\bar X-\mu)}{\sigma} and \sum_{i=1}^n\frac{(X_i-\bar...

• Replies: 2
• Views: 1,621
06-22-2013, 09:06 PM
40. ### Factor Analysis: Creating Reliable Scales

Hello all. I have a question I hope someone can help me with. I items which I have run PCA on and come up with 8 factors from about 20 vairables....

• Replies: 3
• Views: 1,590
06-22-2013, 03:27 PM
41. ### p-value associated with Kruskal Wallis with multiple comparison?

I have a data set that shows the differences between 3 different controllers of a biomechanical system on the same performance metric (specifically,...

• Replies: 0
• Views: 1,437
06-22-2013, 03:18 PM
42. ### Is repeated measures ANOVA appropriate for my data set?

My project involves designing various controllers of a biomechanical system, and then once the controller design is complete, testing each controller...

• Replies: 0
• Views: 1,241
06-22-2013, 01:37 PM
43. ### Cumulants of non central chi-square distribution

Cumulant generating function is defined by logarithm of Moment generating function. K_X(t)=\log M_X(t) let X is a non central \chi^2 variate...

• Replies: 2
• Views: 2,913
06-22-2013, 09:59 AM
44. ### How do you report Fisher's Least Significant Differences results?

Hi, I've been looking online to see how to report LSD results but I cannot find anything anywhere! I understand for a lot of post hoc/planned...

• Replies: 0
• Views: 1,245
06-22-2013, 08:33 AM
45. ### Assumptions of a 2 proportion z-test - help!

Hello, I recently inherited an excel workbook from someone who transferred out of my current company. Within this workbook, He was comparing...

• Replies: 1
• Views: 2,639
06-22-2013, 03:43 AM
46. ### An Exercise of noncentral [math]\chi^2[\math] distribution.

Let Y_1,\ldots,Y_n be independent random variables with Y_k distributed as N\sim(a_k,\sigma^2) , and \bar Y=\sum_{k=1}^{n}\frac{Y_k}{n} denote the...

• Replies: 0
• Views: 1,190
06-21-2013, 09:20 PM
47. ### Appropriate analysis

Hi, Im looking at running a non-parametric test on ranked data. I have two variables. Each subject completed two conditions which included 3...

• Replies: 1
• Views: 1,509
06-21-2013, 09:20 AM
48. ### calculating p-value from resampling of the null distribution

Hi all, i am a PhD student in Bioinformatics and i'm dealing with some statistics issue in my reasearch; i was hoping you could lend me a hand :D ...

• Replies: 0
• Views: 1,942
06-21-2013, 08:21 AM
49. ### How to generate optimal values of the weights

How do I generate optimal values of weights for index in Excel?

• Replies: 1
• Views: 2,102
06-21-2013, 07:27 AM
50. ### Patient data - Choosing the Right Model

Hello, I just finished up my first year as a statistics major and have been assigned a summer project from my employer at the hospital near my...

• Replies: 4
• Views: 1,647
06-21-2013, 03:15 AM
51. ### Question about calculating standard errors with BRR replicate weights

I’m analyzing a survey (the PSS) in which each respondent is a school. I’ve been provided with 88 BRR replicate weights which I was hoping to use to...

• Replies: 0
• Views: 1,584
06-20-2013, 06:08 PM
52. ### Statistical analysis question

In my study I am looking at whether social class & race of a job applicant influence the applicant’s job promotion…so IV1 = social class of...

• Replies: 10
• Views: 1,925
06-20-2013, 03:46 PM
53. ### A uniform distribution problem

A person's score in a test is uniformly distributed over . She is permitted three attempts at the test. However, after the first attempt, she is...

• Replies: 2
• Views: 1,532
06-20-2013, 01:40 PM
54. ### Modeling overlapping groups

What I am trying to do is show hiring managers how adding a number of seemingly reasonable requirements to a job may reduce the number of candidates...

• Replies: 4
• Views: 1,124
06-20-2013, 01:34 PM
55. ### Which test should I use for multiple variables, multiple sites & non-parametric data?

Hi All, I've spent the past two weeks trying to figure out which test to use and have gotten nowhere so hoping someone here can help! I have been...

• Replies: 4
• Views: 1,368
06-20-2013, 01:12 PM
56. ### Difference in Profit Proportions

What test can I use to determine if two profit percentages are statistically different? ex. In 2011 a company sold $200 worth of products with$50...

• Replies: 0
• Views: 867
06-20-2013, 09:20 AM
57. ### Assumptions MWU-Test

Hi, I just don’t know how to go on with my research at the moment, I haven’t found answers to my questions in any forums or papers, so it would be...

• Replies: 0
• Views: 1,637
06-20-2013, 07:12 AM
58. ### Determining the p-value of an H0: A≠B

I noticed that there seemed to be a relation between 2 variables I measured on an experiment. I got the correlation coefficient and the slope for...

• Replies: 1
• Views: 18,040
06-20-2013, 03:23 AM
59. ### Which Test should I use

Hi. A have a group of 200 law students who have finished their first year. They have completed a total of 7 courses. I am interested in being able to...

• Replies: 1
• Views: 1,314
06-20-2013, 03:01 AM
60. ### MLE of multinomial distribution with missing values

Hi, I am trying to solve a problem and the results I get seem counter-intuitive. We randomly throw n balls into an area partitioned into 3 bins...

• Replies: 5
• Views: 1,741
bit
06-19-2013, 08:17 PM

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