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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: 196,509
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: 66,594
09-30-2005, 09:44 AM
1. ### Geometric Distribution MLE

Consider carrying out a sequence of Bernoulli trials where the probability of success is pi in each trial. We stop when the first success occurs. Let...

• Replies: 3
• Views: 10,870
01-14-2010, 10:37 AM
2. ### Categorical and ordinal scale....chi square?

Hi I am seeking help on this issue. I have a categorical variable namely gender (male x female) and an ordinal variable about perception of a...

• Replies: 18
• Views: 10,851
08-24-2012, 01:28 PM
3. ### Scaled data vs. normalized data

1.Are they the same? 2.Why we need to scale the data especially when we want to compare the dist of the data for (say) 2 samples? Some say to make...

• Replies: 3
• Views: 10,843
03-15-2010, 07:27 AM
4. ### How do determine min sample size for auditing medical claims by medical records?

I have a sampling methodology question I'm in need some statistical expertise with: I'm trying to determine how to calculate the minimum sample...

• Replies: 3
• Views: 10,820
08-17-2010, 10:15 AM
5. ### Help with predicted value problem using regression equation

Use the computer display to answer the question. A collection of paired data consists of the number of years that students have studied Spanish and...

• Replies: 0
• Views: 10,817
11-13-2006, 03:00 PM
6. ### Degrees of freedom for t-test for difference of proportions?

I'm doing a t-test for the difference between two proportions in a small sample context where the two sample sizes add up to less than 30. I'm...

• Replies: 4
• Views: 10,809
12-13-2010, 12:10 AM
7. ### interpreting Likert scale

Hello! So the research is about motivations on microblogging. A 5-point Likert scale was used. 1=Never; 5=Always I have the mean, median,...

• Replies: 3
• Views: 10,801
12-04-2010, 03:32 AM
8. ### MGF of lognormal distribution

Let x ~ N (μ,σ^2 ) and consider the lognormal r.v. y= e^x. Given the MGF of the normal distribution M_x (t)= e^((μt+0.5σ^2 t^2)). How to compute...

• Replies: 2
• Views: 10,797
10-08-2009, 12:46 PM
9. ### Comparing distributions, Two-Sample KS-test and Bonferroni

Hi there, The following is my problem for which I’m grateful to have any advice/opinions: I measured the distances animals moved in 3 different...

• Replies: 1
• Views: 10,790
02-19-2006, 05:14 PM
10. ### logist regression - standardized estimates

Hello, can anyone help me with a brief explanation? :confused: Usually I use the "stb" model option while running the proc logistic in sas to...

• Replies: 6
• Views: 10,777
06-15-2011, 05:17 AM
11. ### SPSS Output: Increasing "R Square Change" Value

Hello, I have preformed a stepwise regression on my data set using SPSS. In the out put table the "R Square Change" value for the second model...

• Replies: 3
• Views: 10,773
07-03-2012, 05:02 PM
12. ### Unequal group sizes and chi square test of independence

I began working on a project that compares birth outcomes of women in a case management program (n = 270) to the birth outcomes of the general...

• Replies: 1
• Views: 10,760
10-21-2013, 05:45 PM
13. ### Is normal dist OK for these count data?

Hello, I am modelling some count data (ANCOVA). I use R for statistical computing. I am not sure if I must use a glm with poisson errors.

• Replies: 3
• Views: 10,748
09-03-2013, 05:49 AM
14. ### lognormal

How do I find the p50 value in a lognormal distribution given p10 and p90 using excel/@RISK ??

• Replies: 7
• Views: 10,739
BGM
01-15-2011, 05:59 AM
15. ### How to convert Likert scale scores into interval/ratio

How can I convert my data obtained on Likert scale into the scores on which I can apply Correlation, Regression and Factor Analysis?

• Replies: 2
• Views: 10,725
10-31-2009, 09:08 PM
16. ### Degree of freedom for error

I have performed an ANOVA with three variables on XLSTAT, and I am looking for the freedom of error for each indvidual main and interaction effect. ...

• Replies: 1
• Views: 10,714
01-13-2009, 10:57 AM
17. ### Usage of the mean with ordinal data

WARNING: This will be a long post! Also, I am no statistics expert, so I tried to explain myself as best as possible. I will be entering grad...

• Replies: 2
• Views: 10,691
11-07-2007, 10:38 PM
18. ### True experiment requirements

I know this is more of a R&D question, but it is for a statistics class. If subjects are randomized to 1 of 4 groups, none of which is a control...

• Replies: 4
• Views: 10,680
07-07-2008, 03:40 PM
19. ### Difference between one-tail and two-tail t test

Hey I am a newbie here. Think in real simple terms. I am having trouble understanding the differnece between one-tail and two-tail t tests....

• Replies: 2
• Views: 10,678
11-16-2008, 09:55 AM
20. ### Rejection Region

I had a question on an exam recently that I got correct by accident. The question is as follows: In testing H=50 and H>50, suppose we reject H...

• Replies: 2
• Views: 10,670
05-09-2008, 07:13 PM
21. ### Intra-individual variability measure

I'm looking for a simple means for expressing intra-individual variability. Let's say Participant 1 has 5 beers on one occasion, 10 beers on another...

• Replies: 1
• Views: 10,667
04-12-2011, 06:28 PM
22. ### mode of the chi-square distribution

I don't understand why the mode of the chi-square dist is df-2. With three categories, the mode would be 1, that is, the distribution would have its...

• Replies: 10
• Views: 10,655
11-16-2010, 11:42 PM
23. ### Probabiloty and distribution help

1. For quality control purposes, a company that manufactures copper sheets routinely takes samples from its production process. Since its product is...

• Replies: 2
• Views: 10,642
05-31-2015, 01:26 PM

I guess there are automated methods but I am referring to manual selection. Like: first finding out which variables have significant individual...

• Replies: 4
• Views: 10,637
04-07-2012, 12:01 PM
25. ### Delphi study / 9 point Likert scales

We are conducting a Delphi study. Each statement in our questionnaire is scored on a nine point likert scale ranging from 1(strongly disagree) to...

• Replies: 3
• Views: 10,636
12-02-2006, 03:53 PM
26. ### please i need help in solving these questions

hi all, please can anyone help me :( 1. The internal auditing staff of an local manufacturing company performs a sample audit each quarter to...

• Replies: 21
• Views: 10,630
BGM
12-10-2011, 04:57 PM
27. ### Goodness of Fit Vs Predictive Ability

Hello, What is the difference between predictive ability and goodness of fit? Ir ead that c statistic and concordance, discordance are neasure of...

• Replies: 0
• Views: 10,625
02-22-2010, 06:08 PM
28. ### post hoc test for chi-square

ok this might be a newbie question but lets say I have data that I have cross tabbed for location and level of agreement. A ...

• Replies: 6
• Views: 10,622
12-22-2011, 06:07 PM
29. ### Homework help (the empirical rule)??

Hello, Can anyone help me with this problem? SAT math scores have a bell shaped distribution with a mean of 515 and a standard deviation of 114. ...

• Replies: 1
• Views: 10,600
10-30-2010, 01:22 AM
30. ### Hypothesis Test concerning difference in proportion- Where did i go wrong???

Hey all, The answer I get is not amoung the answers offered. I'd appreciate some help in telling me where I went wrong!! In order to determine...

• Replies: 7
• Views: 10,598
12-18-2007, 04:35 PM
31. ### Interaction is significant but posthoc is not significant

I'm running a mixed model ANOVA with 16 levels (2X8). The first factor is gender with 2 levels (between subject factor) and second factor is time...

• Replies: 5
• Views: 10,591
01-20-2009, 09:30 PM
32. ### Wilcoxon signed rank test with unequal sample size?

Hello all, I would need a two sample unequal sample size paired nonparametric test to compare two distributions. I believe Wilcoxon signed rank...

• Replies: 3
• Views: 10,548
11-10-2010, 10:11 AM
33. ### Sig 1 tailed is ,000. What does this mean

For my studie i made a correlation matrix with a moderating value of man and women. For women the sig. 1 tailed came out with 0,000 I am not sure...

• Replies: 2
• Views: 10,515
01-15-2012, 01:46 PM
34. ### calculate the average of the standard error?

Hi Folks, I have two estimates that I would like to average: N1 = 68.7 (SE = 13.6) N2 = 81.6 (SE = 15.5) Average N = 75.2 (SE = ?). Can...

• Replies: 2
• Views: 10,495
07-19-2011, 11:59 AM
35. ### Comparing correlations

I've asked caregivers to complete three scales relating to the same group of persons with an intellectual disability. I'll call the scales A, B, and...

• Replies: 2
• Views: 10,495
06-01-2010, 07:13 AM
36. ### 2 way ANOVA post hoc tests SPSS

:wave:I have been using 2 way ANOVAs SPSS in base 15.0 to look at the effect of two fixed factors (treatment and brain region) on a dependent...

• Replies: 4
• Views: 10,494
05-14-2013, 02:53 PM
37. ### When to use 5pt vs. 7pt Likert Scale?

I am working a survey for physicians, and am planning on utilizing a Likert Scale for an assessment. I've heard different things from a few...

• Replies: 4
• Views: 10,474
11-20-2008, 03:07 PM
38. ### ordered array vs. stem and leaf

I am a beginner stats taker and terrible at math. my book does not explain this well: When is it best to use an ordered array vs. stem and leaf?...

• Replies: 0
• Views: 10,456
02-02-2011, 01:37 AM
39. ### Shapiro-Wilks Test

Hi all I know that when doing a Shapiro-Wilks Test you need a W value close to 1 for normality to be adequately met. But how close is close? For...

• Replies: 6
• Views: 10,449
05-05-2009, 11:08 AM
40. ### How do you find percentiles for Gamma and Poisson Distributions

Hi, I want to find the value of the 90th percentile for two sets of data that I have. One set of data follows a Gamma Distribution, the other...

• Replies: 2
• Views: 10,446
07-03-2012, 10:29 PM
41. ### variance of the ratio (Y/X)

I found the formla of the variance of two ratios y = interest variable x = auxiliar variable N = population size n = sample size r = ∑yi/∑xi...

• Replies: 2
• Views: 10,431
07-07-2011, 01:10 AM
42. ### [SOLVED] Suggest method of analysis

Hi, i have two sets of data one control and the other treated. Pl. suggest a best method/s of analysis to effectively study the treatment effects....

• Replies: 6
• Views: 10,417
10-02-2008, 08:28 AM
43. ### t-test with log-transformed data

I am working with cost data which is highly right skewed and comparing the costs between 2 groups. I deemed it best to perform a log transformation...

• Replies: 1
• Views: 10,407
06-22-2012, 11:45 AM
44. ### Normal Distribution and Sampling

A waitress believes the distribution of her tips has a model that is slightly skewed to the left, with a mean of 10.50 and a standard deviation of...

• Replies: 2
• Views: 10,376
03-02-2012, 09:30 PM
45. ### Trend Analysis

What are the degrees of freedom in trend analysis? And what goes in the denominator? Does it matter what type of trend analysis you are doing, or...

• Replies: 4
• Views: 10,354
12-06-2005, 11:17 PM
46. ### p-value (linear regression in R)

Hi, I am trying to answer a question about linear regression. I have to do a linear regression between xaa and aus variables and find the...

• Replies: 5
• Views: 10,339
05-07-2011, 11:12 AM
47. ### ANOVA, assumptions mandatory?

So on numerous websites, which of course we can trust completely ;) I've run across arguments that the normality and homogeneity assumptions for...

• Replies: 13
• Views: 10,329
09-12-2008, 07:44 AM
48. ### Regression - Assumption of independence

Hello, One assumption of linear regression is that the Y values are independent. This means that in drawing the sample, the values of Y observed...

• Replies: 1
• Views: 10,318
01-08-2010, 01:26 PM
49. ### confused about sample mean vs sampling distribution mean

I got this true/false question Consider an infinite population with a mean of 100 and a standard deviation of 20. A random sample of size 64 is...

• Replies: 6
• Views: 10,309
02-18-2011, 08:06 PM
50. ### statistics “with technology” and “without technology”

In the answer section of my statistics book it lists the answer “with technology” and “without technology”. What and why is there a difference? Is...

• Replies: 0
• Views: 10,304
11-02-2007, 11:51 AM
51. ### x-bar distribution

Question: Is the sampling distribution of x-bar always normally distributed, regardless of the size of the sample n? Answer: No Is this...

• Replies: 2
• Views: 10,300
11-19-2010, 04:30 PM
52. ### significant difference between three proportion??how??

hello thank you for best sit. I have a question. when we have just three proportion how we do say there are significant difference between them?...

• Replies: 7
• Views: 10,272
hol
05-23-2011, 12:47 AM
53. ### CFA vs. SEM

I hypothesized a 4-factor model for my data and SEM supported this, but CFA suggested 5 factors (see results below). Why might this difference be and...

• Replies: 10
• Views: 10,271
11-03-2011, 06:33 PM
54. ### R question/Command to calculate Confidence Interval of a Mean?

Does anyone know what command I should use in R for a confidence interval test on a one-sample mean? I know the command to estimate the...

• Replies: 2
• Views: 10,263
01-04-2012, 08:58 AM
55. ### Confidence Interval and P-value method

Here is the question and it's actually 2 parts. Use the confidence interval method: For a sample of 25 items from a normally distributed...

• Replies: 3
• Views: 10,253
04-01-2008, 11:43 AM
56. ### Nonparametric 3 factor ANOVA

I am trying to find a nonparametric equivalent for 3 within subject factors ANOVA test. I checked Friedman test, but all the examples that I found...

• Replies: 3
• Views: 10,247
05-07-2013, 10:14 AM

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