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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: 197,089
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: 66,920
09-30-2005, 09:44 AM
1. ### Nonparametric test choice for skewed data

Hello, My first thread on the board... I posted this to the SPSS-X list , but thought this forum may be more appropriate. I was wondering if...

• Replies: 8
• Views: 9,832
01-12-2007, 04:05 PM
2. ### Skewness of a sum of independent lognormal variables?

Hey, I have a set of lognormally distributed independent variables X1,...,Xn each with different E and Var for k=1,2...n. (So each Xk has its own...

• Replies: 7
• Views: 9,826
11-12-2010, 07:10 PM
3. ### Question regarding finding midpoints, relative frequency and cumulative frequency

I was given a list of numbers as listed below: 91 472 279 249 530 376 188 341 266

• Replies: 8
• Views: 9,826
04-02-2011, 01:58 PM
4. ### Interpreting the results of Kruskal-Wallis QUESTION

If I have used Kruskal-Wallis to compare 3 data sets of diameter values for 3 different populations of trees, and the results are significant...

• Replies: 4
• Views: 9,822
02-04-2012, 07:41 PM
5. ### Interquartile range: Why add 1 to the sample size

My understanding is that the interquartile range is calculated by taking the difference between the (N+1)*0.75th observation and the (N+1)*0.25th...

• Replies: 1
• Views: 9,816
BGM
10-30-2010, 02:52 PM
6. ### sample means and probability

Seventy million pounds of trout are grown in the U.S. every year. Farm-raised trout contain an average of 32 grams of fat per pound, with a standard...

• Replies: 1
• Views: 9,813
03-25-2008, 07:25 PM
7. ### What are reverse confidence intervals?

Can someone just give me a brief overview of how these differ from regular confidence intervals? I can't find anything on google. Never heard of...

• Replies: 6
• Views: 9,813
c2q
04-08-2011, 03:00 PM
8. ### Deck of cards and probability (non replacement)

Hi can someone help me Im stuck. When selecting cards from a deck without replacement: What is the probability that the first card is a four and...

• Replies: 8
• Views: 9,810
11-11-2010, 09:40 PM
9. ### Help Regarding Standard Deviation in SPSS

Hi, I am working on a HR Project. This is my situation: 14 Questions, all are objective type, they have five options: 1=Strongly disagree,...

• Replies: 3
• Views: 9,807
05-16-2011, 12:44 AM
10. ### Relatively easy hw problem

The problem seems relatively easy. No big formula is required (i think?) Well, this is the question A newspaper article about the results of a...

• Replies: 2
• Views: 9,801
11-17-2010, 04:05 AM
11. ### confused..Kruskal-Wallis!,mutipe Mann-Whitney!,ANOVA!

Hi everyone I’m doing a research on three different diseases I’m measuring a protein in theses diseases using an ordinal score The scores are...

• Replies: 7
• Views: 9,792
12-06-2009, 09:21 AM
12. ### The other formula for SD

We all know the formula for SD But I recall a pal of mine long long ago showing me another formula for working out SD that - he argued - was far...

• Replies: 7
• Views: 9,766
01-01-2013, 03:36 PM
13. ### Contrasts in R for two-way and three-way interactions

I am new to using R and have just performed some mixed effect models which have significant 2-way and 3-way interactions. My question is now that I...

• Replies: 8
• Views: 9,765
07-14-2011, 07:31 AM
14. ### Expected Value of normally distributed random variables

Given two independent random variables Y and W. Where Y is distributed as N(0,1) and W is distributed as N(0.100). a) Show that E = 1 and E = 0...

• Replies: 18
• Views: 9,743
11-03-2011, 08:06 PM
15. ### Standard Error for Percent Change

Would greatly appreciate some assistance calculating the standard error for a percent change, so that I can construct 95% confidence intervals and...

• Replies: 0
• Views: 9,742
07-03-2008, 02:43 PM
16. ### Practical regression issue - correlated regressors

Hi guys, I have a business problem where I'm trying to run a linear multivariate regression model to predict a profit variable with some internal...

• Replies: 2
• Views: 9,730
05-11-2010, 06:53 PM
17. ### nonparametric test percentages?

I have a data set that doesn't fulfil the assumptions of normal distribution and equal variances. SInce it's percentage values, the recommended...

• Replies: 8
• Views: 9,722
06-28-2010, 05:01 PM
18. ### Matched Pair vs non-pooled t test

I'm a little bit confused as to when we would do a matched pair test and when we do a non-pooled t-test? I know that in order for us to do a matched...

• Replies: 1
• Views: 9,719
04-30-2008, 06:57 PM
19. ### Question about beta coefficient and p value

Hi, I conducted univariable linear regression. One of the variables has resulted in a zero beta coefficient and the significance is <0.02. How...

• Replies: 3
• Views: 9,718
06-22-2009, 06:09 PM

I have my book which is sort of like Greek to me, but I have read the chapter several times, and tried to work some of the problems, but the examples...

• Replies: 26
• Views: 9,707
05-19-2008, 11:23 PM
21. ### Expected Value of X

I'm asked to find the excpected value of x-bar, but I'm not sure what method to use here. The information I have: According to AAA, the average cost...

• Replies: 1
• Views: 9,707
11-22-2006, 11:27 AM
22. ### mean signed and unsigned (absolute) error

Hi, I'm trying to compare several computational chemistry methods with an experimental method, and some of the statistics of choice are the mean...

• Replies: 0
• Views: 9,690
06-03-2010, 11:38 AM
23. ### Confidence interval ratio of variances

Hi guys..I simply don't know where to start and my book isn't helpful at all (it doesn't mention this)....please help! A study was undertaken to...

• Replies: 12
• Views: 9,681
10-30-2008, 01:25 PM
24. ### Statistics - Comparing Dose Response Curves

So I've got a stats question for anyone who can help; "You are testing the effects of a new drug that has been synthesized as an example of a...

• Replies: 4
• Views: 9,680
10-25-2012, 05:31 AM
25. ### Interpretation of a oneway random-effects Intraclass Correlation Coefficient (ICC)

I'm working with the following setup: I have two different judges rating suitability on a Likert-type rating scale for n subjects. The judges are not...

• Replies: 2
• Views: 9,676
10-28-2008, 07:35 PM
26. ### sampling distribution

i have been trying to do this for while, but couldnt figure out how. AUTO ACCIDENTS A study of rush hour traffic in San Francisco counts the...

• Replies: 3
• Views: 9,673
01-17-2007, 05:48 PM
27. ### Computation of Mean/Average Z-Scores

Hello, EDIT: I am having trouble uploading my .xls file. I also tried putting the .xls into a .zip but I will always receive an error message. How...

• Replies: 1
• Views: 9,664
08-30-2011, 05:42 PM
28. ### Levene's Test for Equality of Variances

Hello everyone, Would you please help me in the computation of F-ratio in Levene's Test for Equality of Variances for two groups,i.e. in t-test? I...

• Replies: 1
• Views: 9,657
08-01-2011, 06:01 PM
29. ### Using SPSS to calculate P value? How to do it?

I'm using the SPSS software, and I have been given two columns of data e.g. one column for weight and the other for height how would I go about...

• Replies: 1
• Views: 9,656
04-09-2013, 09:54 AM
30. ### Help me out: Computing SE CV SED LSD

Dear All, In calculating standard error of mean (SE) and coefficient of variation (CV) for summary table of means exported to excel from SAS anova...

• Replies: 0
• Views: 9,639
09-13-2006, 08:19 AM
31. ### tukey or scheffe in post hoc after ANOVA

hi, i have question on one way ANOVA. in my lecture notes it was stated only tukey . but is it ok also When the three groups are not of equal...

• Replies: 2
• Views: 9,606
10-13-2010, 10:27 AM
32. ### Expectation of reciprocal of a Normal Distribution

Let X~N(a,b) How can I calculate E(1/X) ?

• Replies: 5
• Views: 9,599
09-09-2009, 12:03 AM

High school students who take the SAT mathematics exam a second time generally score higher than on their first try. The change in score has a...

• Replies: 1
• Views: 9,584
01-04-2006, 07:53 AM
34. ### Lightning Strikes statistics question

I can't figure out this problem The number of lightning strikes on a square kilometer of open ground in a year has a mean of 6 and a standard...

• Replies: 5
• Views: 9,582
03-30-2009, 12:54 PM
35. ### variance of log(s^2)

Y1,...,Yn are i.i.d. random variables from N(mu, sigma^2) distribution. s^2 = sum/(n-1) , where i = 1,...,n Find var(log(s^2)) My approach:...

• Replies: 2
• Views: 9,579
12-01-2010, 11:18 AM
36. ### S.O.S. - effect size indexes for nonparametric tests

Hi there folks, I am carrying out a study (repeated measures design) employing nonparametric statistics ( Friedman's and Wilcoxin signed rank...

• Replies: 1
• Views: 9,574
12-19-2006, 07:23 AM
37. ### Showing Beta Distribution is from Exponential family

I've been trying to show that the beta distribution is from the exponential family. So far i have: f(y│μ,φ)=Γ(φ)/Γ(μφ)Γ((1-μ)φ) y^(μφ-1)...

• Replies: 2
• Views: 9,564
06-22-2011, 08:50 AM
38. ### P-value when one data set has all zero values

Hi Forum :) I am currently comparing data sets of insects caught in pitfall traps from two sites with Mann-Whitney tests. There are 20 samples in...

• Replies: 20
• Views: 9,561
11-15-2011, 11:37 PM
39. ### One-tailed Mann Whitney U test

Hi Everyone I am attempting to analyze data that I have collected in the field for my senior thesis. I have been advised to use a Mann Whitney U...

• Replies: 2
• Views: 9,557
11-17-2011, 05:38 PM
40. ### Tukey results

I was wondering if anyone could provide any assistance in showing me how to report Tukey HSD test results in a table, e.g., what test statistic to...

• Replies: 1
• Views: 9,556
03-27-2006, 11:52 AM
41. ### Critical values for cointegration test?

Does anybody know where I can find critical values for the cointegration test? I need to know the critical values corresponding to how many...

• Replies: 2
• Views: 9,551
08-18-2007, 10:17 AM
42. ### Stratified Samples ???

Hi, I'm having some trouble with this question. The question asks Stratified samples are widely used to study large areas of forest. Based...

• Replies: 4
• Views: 9,542
09-17-2006, 07:45 PM
43. ### Mann Whitney U - P Value of 0.0000

Good Afternoon all, I am using a Mann Whitney U to compare two populations the data ranges from (-2 to 2). I have already done this on 4...

• Replies: 9
• Views: 9,539
05-11-2013, 02:33 PM
44. ### Mann-Whitney U Test or One-way ANOVA - Welch F test?

I have two groups (Site 1 and Site 2) and would like to look at differences between the sites. The data violates assumptions of homogeneity of...

• Replies: 6
• Views: 9,534
klm
11-18-2011, 03:35 AM
45. ### Expected Value of AB

Let A=f(x)=(3/8)x^2 where 0<=x<=2 B=g(x)=(1/4)x^3 where 0<=x<=2 I need to find Cov(A,B), I know Cov(A,B) = E-EE, but how to calculate E??

• Replies: 4
• Views: 9,532
05-18-2011, 01:31 PM
46. ### Doubt on partial correlation SPSS output

Hello there, I'd need some help interpreting the output of a partial correlation analysis. The background is quite simple: I have two group of...

• Replies: 7
• Views: 9,528
01-27-2011, 10:31 AM
47. ### Controlled Variable, replication, and randomization

Hi all, I'm stuck on this homework question dealing with the topics mentioned in the title of this thread. The quality control department of a...

• Replies: 0
• Views: 9,508
09-17-2010, 11:58 AM
48. ### Pearson correlation coefficient P-value statistic?

Original question: How was the P-value for the Pearson correlation coefficient calculated? What is the number of degrees of freedom of the test...

• Replies: 1
• Views: 9,503
12-19-2010, 01:55 PM
49. ### Chi square test, expected frequency less than 5

Please someone help me out. I have three independent group data (Group A, B, and C), which sample size is 128, 100, and 31. Among those, the...

• Replies: 5
• Views: 9,501
07-06-2010, 10:52 AM
50. ### How to find level of confidence?

Say I have upper bound and lower bound of a confidence interval and I know standard deviation too.how can I deduct level of confidence from this...

• Replies: 2
• Views: 9,463
10-06-2010, 03:51 AM
51. ### finding p-value when F-value and df's are known

Websites like this: http://www.danielsoper.com/statcalc/calc07.aspx gives you exact p-value when u enter F-value, and df's. Is there any way we can...

• Replies: 3
• Views: 9,459
02-24-2010, 05:30 AM
52. ### Significance (t-statistic)

I'm not sure how to answer this one: Q: You are testing Ho: mu = 0 against Ha: mu (does not equal) 0 based on an SRS of 20 observations from a...

• Replies: 3
• Views: 9,451
12-04-2005, 10:22 PM
53. ### t test in excel

HI there, I am trying to compare the means from 2 independant groups in excel. I am using excel 2003 and dont have any of the data anaylsis add...

• Replies: 2
• Views: 9,447
11-26-2008, 03:14 PM
54. ### Teaching yourself statistics

I couldn't find a similar topic in Search so I'd appreciate any feedback you can share. I want to teach myself statistics and probability. I...

• Replies: 6
• Views: 9,426
05-04-2010, 02:06 AM
55. ### Calculating Confidence Intervals for survey results

Hello I have what is probably a fairly basic question! I am conducting a number of surveys looking at expenditure behaviour of audiences at an...

• Replies: 2
• Views: 9,424
03-23-2010, 01:11 AM
56. ### How to find the 70th percentile and Q3

Ok so lets say that N(4,3) how would I find the 70th percentile and Q3. I know that the values would be something like (-5, -2, 1,4,7,10,13) based on...

• Replies: 4
• Views: 9,421
BGM
11-25-2011, 01:32 AM
57. ### Finding a least squares fit for f(x)=A*cos(Bx)

Hello, I'm trying to derive the solutions for the estimates of A and B for the equation f(x)=A*cos(Bx) or ...cos(Bx+C) using least squares. I have...

• Replies: 5
• Views: 9,399
07-06-2008, 11:37 PM
58. ### Should i use ancova or anova? One continuous variable and one categorical variable.

I have one dependent variable that is continuous. It is the score on a particular achievement test. I have two independent variables. One categorical...

• Replies: 13
• Views: 9,399
03-27-2013, 09:29 AM

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