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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: 196,643
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: 66,668
09-30-2005, 09:44 AM
1. ### 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: 10,676
11-16-2010, 11:42 PM
2. ### t distribution for Proportion impossible?

Good afternoon, What are the reasons that we only use Z distribution for proportion confidence intervals, but we can use both Z and t...

• Replies: 10
• Views: 18,764
BGM
02-23-2011, 05:01 PM
3. ### Dependant and Independant variable

Hi I have a very simple scenario. I have two variables - Educational technology and Achievement, both continuous. I have also have number of sub...

• Replies: 10
• Views: 4,017
12-13-2010, 10:04 AM
4. ### E(X), E(Y) and E(X&Y)

I have solved E(X), E(Y) and E(X&Y) before but not when multiple x's and y's are given. I honestly do not know how to do it. Kindly enlighten my...

• Replies: 10
• Views: 3,048
03-09-2011, 03:27 AM
5. ### Standard Deviation with values of zero in population

Hey, let's say I want to find the standard deviation for a small population, and a lot of the results = zero, is there a way to compensate? For...

• Replies: 10
• Views: 8,703
05-30-2011, 11:23 PM
6. ### One-way ANOVA homework help

My teacher asked the following (and the first part of my answer is included): 1. We are interested whether Motivation (mot) is different among...

• Replies: 10
• Views: 3,224
12-02-2011, 06:17 PM
7. ### Determining influence on test score

Hello, I'm trying to determine how some tasks (nominal, ordinal) on one test influence the total score of the test (ratio). As I searched, linear...

• Replies: 10
• Views: 2,821
08-01-2011, 10:08 AM
8. ### Sig Test

Uhhhhh!!!! I don't know what the heck I'm doing. Two samples.... Sample one.... let's call them the 'hairy helmets'.... # = 49, mean = .83,...

• Replies: 10
• Views: 4,071
08-24-2011, 06:13 PM
9. ### When to assume Normality

I am working with a rather large sample (approximately 120). Typically, I would not have any issues justifying normality due to the large sample size...

• Replies: 10
• Views: 11,126
10-15-2011, 07:43 PM
10. ### 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: 10,311
11-03-2011, 06:33 PM
11. ### Matrix regression: Prove H1=1 (H=hat matrix)

I couldn't find a way to prove this... Prove H1=1 (H=hat matrix; 1=column vector of n 1s) I thought that it's "obvious" since the...

• Replies: 10
• Views: 6,217
11-14-2011, 01:37 AM
12. ### Probability question

This question shouldn't be very hard but I don't know which formula to use or how to go about getting the answer, which is .0668. Here's the...

• Replies: 10
• Views: 2,345
12-05-2011, 05:56 PM
13. ### Regression or Chi-Square?

Hi, I have a question about my project. I am confused whether to use regression or chi-square. I need to find the relationship between the...

• Replies: 10
• Views: 2,389
06-15-2012, 09:19 AM
14. ### 2 Questions on quality improvement

Q1. My p-chart from data below saw that the process is out of control. What should a team do now regarding this data?

• Replies: 10
• Views: 1,927
12-08-2011, 05:02 PM
15. ### martingales problem....

3) Let Xn be a simple random walk starting at 0. Which of the following are martingales and why? a) (Xn )*(Xn) B) (3Xn)*(3Xn)-9n

• Replies: 10
• Views: 2,973
12-13-2011, 12:04 AM
16. ### Sampling from a Sub Sample and Normality Assumption

Say I have sample data (let's call it XYZ) that is drawn from another survey (the US Current Population Survey). This entails that the universe of my...

• Replies: 10
• Views: 2,745
08-10-2013, 03:36 PM
17. ### [Analysis of Variance] - Repeated-measures True or False

1. The magnitude of the variance due to individual differences must be measured and subtracted out of the variance between treatments in the...

• Replies: 10
• Views: 4,609
01-06-2012, 01:49 AM
18. ### Effect size for Wilcoxon Signed Rank

1) i want to calculate the effect size for wilcoxon signed rank (paired sample). I have one group of 10 participants. I know the formula for the...

• Replies: 10
• Views: 15,937
01-04-2013, 04:02 PM
19. ### Help Please. SEM Modelling Problem.

Hi, I need Your help regarding SEM modelling. I don't have background on statistic & been stuck this 2 month on statistic. :( I already read...

• Replies: 10
• Views: 2,517
01-26-2012, 10:23 PM
20. ### [SOLVED] Needing help

Hi, If I have two independent groups (nominal data; normally distributed) and am determining if there is a difference in the groups on 8 or 10...

• Replies: 10
• Views: 2,186
01-28-2012, 08:43 PM
21. ### Help with choosing a statistical test for 2 treatment groups

Can someone help with choosing an appropiate statistical test? I have 2 treatment groups each with more than 4 replicates but for each replicate I...

• Replies: 10
• Views: 2,373
02-06-2012, 03:12 PM
22. ### Why does sample std dev underestimate population std dev?

The subject line is too short for me to word out my question properly: Why does (square root of unbiased estimator for population variance)...

• Replies: 10
• Views: 11,861
SJP
05-08-2012, 09:38 AM
23. ### Why are statistics so 'powerful'?

In referring to statistics and statistics software, I keep seeing the word 'powerful' being used. But what exactly does 'powerful' mean? ...

• Replies: 10
• Views: 3,629
02-18-2012, 08:06 AM
24. ### Cognitive Dissonance about Likert Scale

I am wondering if the typical format of the Likert Scale creates cognitive dissonance for survey respondents. The Likert Scale is bipolar (e.g....

• Replies: 10
• Views: 2,924
03-01-2012, 09:33 AM
25. ### Poll: calculate Rho & Test the significance of Rho

calculate Rho & Test the significance of Rho? Students Ranks in UG Exam (X) Ranks in Entrance Test (Y) A ...

• Replies: 10
• Views: 6,679
03-17-2012, 01:04 PM
26. ### Pool data from individuals in sign test or Fisher's exact test - valid or pseudorep?

Hi all! My intuition is telling me a particular approach is valid even though is appears to go against the principle of not pooling multiple data...

• Replies: 10
• Views: 2,877
03-16-2012, 04:52 AM
27. ### Want to compare students with uneven number of tests taken

Is it possible to compare students with uneven number of tests taken? I would like to repeat this test again, so any assistance for an old guy...

• Replies: 10
• Views: 2,417
05-04-2012, 09:07 PM
28. ### Testing the utility of a model with F-test and T-test

Hello, I just needed some help understanding some concepts. To test a first order model with several predictor variables, you use the F test. I...

• Replies: 10
• Views: 11,786
05-09-2012, 01:39 PM
29. ### One sample t-test

Hi, This is probably an embarrassingly easy problem but I've looked all over the place and I can't seem to find the answer, or at least I don't...

• Replies: 10
• Views: 2,037
05-21-2012, 04:28 PM
30. ### excel stat formula help

launch temperature degrades aggregate reliability by 0.5% per degree below 55 degrees f, at what temperature would the go-nogo criteria of 0.950 be...

• Replies: 10
• Views: 2,974
07-20-2012, 07:05 AM
31. ### Kolmogorov-Smirnov Two Sample test statistic confusion

Hi, What is the test statistic for the Kolmogorov Smirnov Two sample test for testing whether two distributions are the same. I have been using...

• Replies: 10
• Views: 6,104
09-05-2012, 02:00 PM
32. ### significant variables

I am working on a problem and need to determine the stat. significant variables and provide an interpretation on sex? I got the following results...

• Replies: 10
• Views: 2,223
09-25-2012, 08:04 AM
33. ### Significance and multiple outcomes - are we guilty of a form of subgroup analysis?

In a piece of previous research we wanted to see if there was evidence that peoples' ability to perform CPR declined with time. To test this we made...

• Replies: 10
• Views: 2,582
10-04-2012, 12:24 PM
34. ### Regression Coefficient Help

Hello, Thanks in advance for the help everyone, I'm new to this site and I really appreciate it. I am currently working on some research and...

• Replies: 10
• Views: 2,192
12-07-2012, 01:40 PM
35. ### How do you do an F-test for R-square

Hi, How do you do an F-test to test significance of R-square in EXCEL? I have done a linear regression and get R-square = 0.412, how can I test if...

• Replies: 10
• Views: 32,427
01-23-2013, 08:58 AM
36. ### ANOVA with percentages

Hello -- I'm looking for some guidance on how to make my percentage data appropriate for ANOVA. Here is what I have: The dependent variable is a...

• Replies: 10
• Views: 11,976
01-13-2013, 02:20 PM
37. ### Logistic regression versus chi square test for RCT data

Hi My understanding of statistics is basic and mostly on an applied level, but now I have come into a discussion with my project leader and I'm...

• Replies: 10
• Views: 9,952
03-17-2013, 03:46 AM
38. ### probit vs. logit regression

What is the difference between PROBIT and LOGIT regression? How can this difference change the description of analysis results?

• Replies: 10
• Views: 6,617
02-19-2013, 08:36 PM
39. ### Relationship between Two Varibles: Finding the Covariance, Correlation, and IQR

Eight randomly selected students who completed a course in Statistics were asked (1) the number of months between when they finished Algebra and...

• Replies: 10
• Views: 2,134
01-26-2013, 07:38 PM
40. ### GW shark study- You give advice on the stats and I give advice on swim spots ;)

Disclaimer: I am fairly new to the stats side of Ecology, I have carried out a bit of field work in my time but have only come over to the analysis...

• Replies: 10
• Views: 1,851
05-28-2013, 01:35 AM
41. ### What Test to Use to Compare Groups

I'm looking through some data that I have collected from my patients over the past year and wanted to know what Statistical Test to use to see if a...

• Replies: 10
• Views: 1,685
05-28-2013, 03:35 AM
42. ### 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: 1,908
06-20-2013, 03:46 PM
43. ### History & Development of Statistics....

Hi, I have been given the task to write on the Topic: History & Development of Statistics. This task was given to me by my HOD(Head of Department...

• Replies: 10
• Views: 2,131
07-11-2013, 09:16 AM
44. ### Computing confidence for multivariant tests

We'd like to compute an overall confidence value for a test with multiple variants (sometimes with no control). We've used Student's and Welch's...

• Replies: 10
• Views: 2,528
08-28-2013, 07:47 AM
45. ### Help with variable

I'm trying to input data into spss. The variable name is medication and I have coded them all by number, eg: 1=aspirin 2= warfarin 3=...

• Replies: 10
• Views: 4,516
08-21-2013, 03:57 PM
46. ### Higher or Lower Powered studies???

Trying to get me head around if a statistically significant result p<0.05 from a low powered study (20% power for a true relationship in a research...

• Replies: 10
• Views: 2,060
09-19-2013, 08:01 PM
47. ### Normal Distribution

I cant figure out how to do this problem: I have 2 sets of means and 2 sets of SD 1sth graders scored a mean of 25 and a sd of 5 5th graders...

• Replies: 10
• Views: 1,525
09-25-2013, 03:23 PM
48. ### The Silent Majority

The Silent Majority is defined as any group of people who are not outspoken and who are considered to constitute a majority. I have searched high an...

• Replies: 10
• Views: 2,284
11-25-2013, 02:01 PM
49. ### Polychoric correlation (assumptions)

Hi, are there some assumptions for polychoric (tetrachoric) correlation estimation for 0/1 dichotomous variables (such as ratio of 0 and 1)? ...

• Replies: 10
• Views: 3,289
11-22-2013, 10:57 AM
50. ### Confidence interval says the opposite of my hypothesis test is true

Good evening statmasters, I'm working on a problem regarding hypothesis testing. The hypothesis is as follows: drinking .5cm^3 of whiskey per...

• Replies: 10
• Views: 1,756
12-13-2013, 12:42 PM
51. ### normality tests

Hi, I have a specific question that I need clarify. I need to test the normality of some variables, and I used a kolmogorov smirnov test. But the...

• Replies: 10
• Views: 2,133
03-03-2014, 08:54 PM
52. ### Very significant findings - but how do I show that? What's a binomial choice?

Hi all, I'm writing a paper based on one which uses 'binomial choice'. I can't seem to find this in textbooks, what's the most common name for it?...

• Replies: 10
• Views: 1,259
03-23-2014, 08:42 AM
53. ### Trouble with determining the probability of exceding some extreme value

I fitted a normal distribution to my dataset of N=200 lengths. The chi-square test shows it's a pretty good match. I intended to use this normal...

• Replies: 10
• Views: 1,524
04-10-2014, 12:10 PM
54. ### Cohens D and Statistical Significance

I've read that a low scoring Cohens D can be seen to undermine a significant result, however is the opposite true? Can a high Cohens D undermine a...

• Replies: 10
• Views: 3,087
04-16-2014, 01:44 PM
55. ### Statement of significance

Is saying that β1= β2=….= β11=0 (ie: through an F-test) equivalent to saying that "none of the coefficients are significant" (p>0.05 in the STATA...

• Replies: 10
• Views: 2,258
04-23-2014, 01:39 PM

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