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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: 196,631
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: 66,652
09-30-2005, 09:44 AM
1. ### Variance calculation of discrete function (A-B+C-D) - assuming no independence

Hi, wonder if you can help me to verify the calculation below since I am far from being an expert in the field. I have 4 discrete variables...

• Replies: 2
• Views: 4,904
06-18-2013, 08:39 AM
2. ### Can one use different samples in pre and post tests?

Generally I have seen that pre and post intervention tests are applied on the same sample from a population undergoing an intervention. e.g. same set...

• Replies: 5
• Views: 1,945
06-18-2013, 12:19 AM
3. ### Best Way to Analyze Grouped Within-Set Data?

My data set compares the performance/behavior of 2 different controllers of a biomechanical model; the modeled limb is supposed to start at an...

• Replies: 4
• Views: 1,202
06-17-2013, 06:44 PM
4. ### Estimate the unknown parameters

How we could estimate the parameters of non-linear combination of Normal Distribution Random Variables? Thank you

• Replies: 9
• Views: 1,788
BGM
06-17-2013, 12:01 PM

Hello, I am new to this forum and I have limited experience with business stats, so I'm hoping I can find some helpful information for my budget...

• Replies: 1
• Views: 1,150
06-17-2013, 10:41 AM
6. ### statistics 101-statistical tests help!

Hi. I'm really sorry if this question is in the wrong place. I'm trying to figure out and justify statistical tests to be used for a research...

• Replies: 0
• Views: 908
06-17-2013, 10:11 AM
7. ### a good example of ANCOVA in R

Hi, I was wondering if someone can provide a nice and quite complete example of ANCOVA in R. thanks :)

• Replies: 2
• Views: 1,345
06-17-2013, 09:23 AM
8. ### Correlation between two coefficients in linear regression?

Hi, I have a statistics question that has been bugging me. Consider model y=beta1*x1+beta2*x2+epsilon where x1 and x2 are both mean 0 with...

• Replies: 0
• Views: 739
06-17-2013, 05:53 AM
9. ### Help with Kaplan-Meier Analysis

Hello We have done a retrospective study on the survival of fillings in teeth. The situation is as follows: When the filling was lost: Coded as...

• Replies: 2
• Views: 1,492
06-17-2013, 03:56 AM
10. ### Hypotheses Testing regarding Proportion-Question

A computer chip manufacturer claims that no more than 2% of the chips it sends out are defective. An electronics company, impressed with this claim,...

• Replies: 1
• Views: 2,429
06-17-2013, 02:21 AM
11. ### Someone puts Cohen's d in a nutshell, please

Hi, I came across Cohen's d statistic and I would very appreciate if anyone could provide me with a brief explanation of it and with an example...

• Replies: 7
• Views: 96,118
06-15-2013, 05:17 PM
12. ### Transformation to Stabilize Variance

Problem: When Y (> 0) has mean and variance equal to \mu and \mu/n respectively, it is shown in the textbook that the appropriate transformation of...

• Replies: 1
• Views: 2,615
BGM
06-15-2013, 03:06 PM
13. ### Estimating sample size for reliability study

Hello, I'm having problems calculating the required sample size for my PhD study. I have designed my first study, which is comparing moral...

• Replies: 1
• Views: 8,450
06-15-2013, 02:11 PM
14. ### Dealing with multicollinearity. Small N. Enough to remove variable?

Hello all, I'm doing a small N (108 country years), time series, cross country, multiple regression research. - I have 2 independent variables...

• Replies: 2
• Views: 2,153
06-15-2013, 01:42 PM
15. ### sales figures - real problem at work

Hi, I work in retail sales part time. Our sales performance has recently started to be measured against the other colleagues in the shop. Each...

• Replies: 5
• Views: 1,735
06-15-2013, 03:16 AM
16. ### How to group variables for regression analysis?

Hi all, Here's my problem: I have 6 variables: Sex (1,2), Age (18, 18, 19, 21, 25, 25, etc), and four variables describing physical parameters; W,...

• Replies: 2
• Views: 1,224
06-14-2013, 09:45 AM
17. ### Testing for difference between two percentages (using confidence intervals)

Hello, hopefully someone can help me with a question: I wish to test for whether the difference between 2 percentages is significantly different....

• Replies: 0
• Views: 1,919
06-14-2013, 09:43 AM
18. ### Log-linear or logistic regression

Hi, For my thesis, I investigate an issue and me and my teacher as well are doubting on the right way to analyze the research question. The...

• Replies: 3
• Views: 2,220
06-14-2013, 04:44 AM
19. ### Determining true median

I'm sure this question is beneath this forum, but I need help nonetheless. I have a set of data, e.g. 25 23 52.08% 13 25 34.21% 14 20 41.18% ...

• Replies: 0
• Views: 1,300
06-13-2013, 09:07 PM
20. ### How to prove that a sample is statistically significant?

Hello, I've been searching all over the internet for a formula or a test that will help me understand if my sample (41 answers) is statistically...

• Replies: 8
• Views: 2,394
06-13-2013, 05:32 PM
21. ### Sport Statistical Modelling

I am very interested in football and want to create a statistical model for predicting the amount of goals scored by football team by using past...

• Replies: 0
• Views: 1,203
06-13-2013, 03:37 PM
22. ### Correlation

I have a number of studies I am looking at and trying to compare their correlation coefficients ... esentially do a meta-analysis of correlation...

• Replies: 0
• Views: 1,899
06-13-2013, 01:32 PM
23. ### Validating the measurement method used in a study

Hello all ! I'm doing my first study on my master degree level. I have designed a new measuring method. I should probably validate this...

• Replies: 12
• Views: 2,251
06-13-2013, 01:19 PM
24. ### Uncertainty Analysis

Hey guys. So I have a very broad, general question. I am fresh out of school and working my first job. I have been given a dataset and the regression...

• Replies: 2
• Views: 1,354
06-13-2013, 12:25 PM
25. ### conditional expected value with multivariate normal

Suppose I have five random variables, x_1, x_2, a_1, a_2, and u. I know x_1 = a_1 + u and x_2 = a_2 + u. a_1, a_2, and u are all normally...

• Replies: 2
• Views: 2,027
06-13-2013, 11:09 AM
26. ### Variable reduction- which method to use?

I have a panel data set of 121 countries across 10 years and about 43 variables. In theory all the variables should be attempting to measure the same...

• Replies: 2
• Views: 2,717
06-13-2013, 07:21 AM
27. ### Calculating effect size for generalized linear model?

Hi, I have carried out a generalized linear model (in SPSS) with one dependent variable and two factors. Both factors have multiple categories...

• Replies: 0
• Views: 3,968
06-13-2013, 06:36 AM
28. ### Should you transform skewed data when the distribution is expected?

Hi all, I have been discussing this topic all week with people in my department and I can't seem to get a straight answer. I was taught long ago...

• Replies: 16
• Views: 17,375
06-12-2013, 07:29 PM
29. ### Metric to estimate the allowable error/noise in repeated measurments

Hello, I perform two measurements of a variable once a week and I measured a 10.5% difference from week 1 to week 2. How can I tell if the...

• Replies: 0
• Views: 1,213
06-12-2013, 07:24 PM
30. ### Type 1 and type 2 error question, Confused need help thank you!

got it solved thanks

• Replies: 2
• Views: 2,365
06-12-2013, 04:03 PM
31. ### P=0.05

Hello I have a question. I am doing a hypothesis testing, and I get a p value of exactly 0.05. Do I reject the null hypothesis or not, assuming a...

• Replies: 5
• Views: 23,305
06-12-2013, 12:33 PM
32. ### Sampling methods, which is more appropriate?

I have been collecting data on the temperature in an experiment for the last couple months, and I'm interested in the rate of temperate changes. The...

• Replies: 1
• Views: 2,346
06-12-2013, 08:18 AM
33. ### Individual Item T Test Question

Hi. I have a 18 item 5-point Likert type attitudinal pre-test and same 18 item post test. A group of 25 individuals completed a pretest then were...

• Replies: 2
• Views: 1,408
06-12-2013, 04:16 AM
34. ### Interquartile Range

What is the interquartile range of a normal distribution of IQ scores with a mean of 100 and a variance of 225? I think it is 20. I found out the...

• Replies: 2
• Views: 1,853
06-12-2013, 12:29 AM
35. ### How can i compute the following situation in R?

Suppose that an urn contains a number of black and a number of white balls, and suppose that it is known that the ratio of the numbers is...

• Replies: 1
• Views: 1,259
06-11-2013, 11:53 PM
36. ### Paradox in hypothesis testing ?

Hi guys, I thought about something today and I am confused. P value is defined as the probability of seeing a test statistic as the one we saw...

• Replies: 5
• Views: 1,655
06-11-2013, 11:16 PM
37. ### Parametric or non-parametric test ?

Dear the members of group. I have 2 questions regarding my research which has 8 variables in which 6 of them are normally distributed and the rest...

• Replies: 2
• Views: 2,332
06-11-2013, 10:28 PM
38. ### parameter estimation by MLE method

Hi All I need to estimate two unknown parameters (lambda1 and lambda2) by using MLE. I know that they have normal distribution. h = g(lambda1 ,...

• Replies: 4
• Views: 1,278
06-11-2013, 06:14 PM
39. ### Weighted Least Squares through Origin

Consider regression through the origin (i.e. straight line regression with population intercept known to be zero) with Var(ei | xi) = X2i * σ2. The...

• Replies: 0
• Views: 2,845
06-11-2013, 02:42 PM
40. ### test for trend across groups

Dear forum, I would be grateful for some help with a simple problem. I have some data arranged in 5 groups. Each group contains a single data...

• Replies: 3
• Views: 2,807
06-11-2013, 12:53 PM

Can anyone pls help me with the following dilemma: I have 3 different kinds of facilities: public facilities, private facilities and private...

• Replies: 2
• Views: 1,337
06-11-2013, 11:59 AM
42. ### quasi-dependent sample t-test

Hello all, I am doing a pre-post analysis of adherence to clinical measures. My pre and post groups have some identical individuals, but some...

• Replies: 4
• Views: 2,198
06-11-2013, 07:08 AM
43. ### reliable change index and reliability coefficient

Hi. I'm a bit embarrassed at my inability to figure this out even with the vast amounts of information available to me via the internet. Any help is...

• Replies: 3
• Views: 4,457
06-11-2013, 03:00 AM
44. ### Statistical difference between vectors

Hi, I am new to this forum and quite rusty in Statistics after university. Suppose I have M (> 100) number of companies, for each of them I...

• Replies: 1
• Views: 1,469
BGM
06-11-2013, 02:17 AM
45. ### Help needed to understand co-variates and approp. tests for proposed research study

I am currently working on a research proposal, and I am having a really hard time coming up with my data analysis section. Any help you could offer...

• Replies: 0
• Views: 1,073
06-10-2013, 03:44 PM
46. ### Selection of higher order and interaction terms

Hello, I have about 1000 data points with three independent variables and one response. I believe the underlying function is a 3-dimensional...

• Replies: 0
• Views: 926
06-10-2013, 08:22 AM
47. ### Definition of absolute mean difference (application to Gini coefficient)

Hello everyone, This is my first post at the forum. I've tried to find the answer but I couldn't (which may only mean that my searching abilities...

• Replies: 2
• Views: 2,505
06-10-2013, 08:06 AM
48. ### Ranking Method Comparison

Hi, I have 15 items that need to be ranked from 1 to 15. I have two methods to do the ranking, method A and method B. Method A is where I have...

• Replies: 2
• Views: 1,995
06-10-2013, 05:38 AM
49. ### standard error of measurement

Hello I am not a stats expert and I need you help with calculating the standard error of each sample within a collection. For example: Let's...

• Replies: 12
• Views: 2,469
06-10-2013, 12:51 AM
50. ### Example of mode question.

If the population of movies that college students watch during the semester is normal shape with a mean of 40 and standard deviation of 10, what is...

• Replies: 1
• Views: 1,148
06-09-2013, 12:47 PM
51. ### A question in methodology

Good evening, I have a question about methodology, coz i do not know which way to go. For representing av results, I have used descriptive...

• Replies: 7
• Views: 1,251
06-09-2013, 04:03 AM
52. ### Construct Feature Vector

Hi, I am doing a 10-fold cross validation on the training set of the data. I am trying to build a feature vector. I am doing my work in the R...

• Replies: 0
• Views: 961
06-08-2013, 11:44 PM
53. ### Variance of Slope for Linear Regression through the Origin

Given y=b1*xi + ei.... Show Var(B^ | X) = (\sigma^2) / (\sumx^2i I am completely lost how this result differs from the standard var(b) with an...

• Replies: 2
• Views: 4,084
06-08-2013, 10:49 PM
54. ### Survey Findings How to Use - help

I have a dataset of items which use items from the GSS. My sample (N=300) was randomly drawn from 2000 respondents. They are a special population of...

• Replies: 0
• Views: 1,092
06-08-2013, 02:38 PM
55. ### auto-regressive and polynomial models

Hi, I am not a statistician and I want to use the pure auto-regressive (AR) model and/or the polynomial model to solve a prediction problem. I...

• Replies: 0
• Views: 776
06-08-2013, 08:41 AM
56. ### Finding P-value...confusing

The target length for a component is set at 30mm. A random sample of 25 components is selected and the lengths of each are recorded. The result is...

• Replies: 1
• Views: 992
06-08-2013, 08:10 AM
57. ### Standard error calculation fails

Hello all. I would really appreciate any help in solving this problem: There is an interesting article on funnel plots on the web:...

• Replies: 0
• Views: 1,484
06-07-2013, 05:28 AM

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