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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: 196,871
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: 66,817
09-30-2005, 09:44 AM
1. ### Expected value of [random variable squared]

Hi, I am looking for confirmation if my method is correct to find Expected value of . That is E Given that X is a normal random variable with...

• Replies: 3
• Views: 49,927
DAV
10-05-2008, 11:48 AM
2. ### Negative test statistic, what does it prove and what do i do with it?

d) Perform a hypothesis test to see if the true mean time to accelerate from 0 to 100km/hr for eight-cylinder cars is less 14 seconds. In performing...

• Replies: 5
• Views: 48,737
01-09-2014, 08:07 PM
3. ### correlation between categorical and continuous variables

Hello, I have a question regarding correlation between categorical and continuous variables. I know that I cannot use Pearson/Spearman to do this...

• Replies: 3
• Views: 47,722
01-27-2012, 06:28 AM
4. ### K-S test interpretation in R

Dear all I am doing a Kolmogorov-Smirnov test in R in order to test if the two variables are from the same distribution. Turns out that I don't...

• Replies: 3
• Views: 46,577
08-21-2010, 07:27 AM
5. ### Standard Error of the Residuals

Hello, Iknow that the standard error of the residuals of a regression equation is given as the sqare root of SSE divided by the degrees of freedom...

• Replies: 2
• Views: 46,095
12-03-2010, 01:36 AM
6. ### finding UMVUE of parameter 1/(1+λ)

suppose X1,X2,X3 are a random sample of exponential distribution with parameter λ. how can i find UMVUE parameter 1/(1+λ). note: (T=∑Xi,(i=1,2,3);...

• Replies: 1
• Views: 45,009
05-04-2012, 11:24 AM
7. ### Hypothesis testing with no stated standard deviation

My head is going to explode, can someone help before it is too late? Te problem: According to the government, 23% of all American adults have...

• Replies: 1
• Views: 44,664
02-25-2006, 08:35 AM
8. ### How to calculate the overall mean of several Likert scale data?

Hi, I have a set of questionnaire as follow: Perceived Usefulness Rating(5-point Likert Scale) PU01 PU02 PU03 ... I used SPSS to compute...

• Replies: 6
• Views: 44,406
03-05-2012, 06:45 PM
9. ### Outliers in a normal Distribution

So far, all I've been able to figure out is the IQR in percentage is 50%. This is the problem. The percent of the observations that are...

• Replies: 5
• Views: 44,380
10-04-2008, 09:01 PM
10. ### finding UMVU estimator of θ^2

suppose X_1,…,X_n be a random sample of distribution with probability density function f(x)=2/θ *x* exp(−(x^2)/θ),x>0. how can i find UMVU estimator...

• Replies: 1
• Views: 43,634
05-03-2012, 08:45 PM
11. ### What does an outlier in a stem and leaf plot look like?

I have to analyze some displays (e.g. stem and leaf plot, histogram) I have generated for a homework questions from a group of numbers. I have...

• Replies: 6
• Views: 43,501
12-12-2010, 04:06 PM
12. ### Confidence Interval- which is narrower? 95%? 99%?

One of my homework question requires me to explain why 99% is narrower 95% but I think its other way around. Am I wrong or the question is a typo?

• Replies: 2
• Views: 43,307
09-28-2008, 05:40 PM
13. ### Reliability (alpha and inter-item correlation)

Hi I have just conducted the first stage of a test re-test of a scale that consists of 5 items. Where I got Cronbach's alpha of 0.71 This is...

• Replies: 5
• Views: 43,079
12-09-2011, 08:39 PM
14. ### Sufficient Statistic for θ

Hey guys, So Im looking for a sufficient statistic for θ for U(θ, θ+1) Here's what I was thinking. T(X^n)=(min X_{i},max X_{i}) since the pdf is...

• Replies: 11
• Views: 42,145
02-12-2013, 04:48 PM
15. ### finding z-statistic and P value

Hello everyone! I just wanted to know if im doing this correct. The conclusion thing is quite confusing to me. I dont quite get how to find the level...

• Replies: 2
• Views: 41,872
02-25-2010, 10:10 PM
16. ### How calculate intercept with multiple regression

I am familiar with calculating the intercept, etc for a regression equation, but I am confused as to how to calculate the intercept when using...

• Replies: 16
• Views: 41,376
01-15-2014, 12:07 AM
17. ### Help Required in calculating USL and LSL

Hi all, I have a sample of 8 datapoints with a Std. Dev of 0.0195940953204932 and Mean of 0.10125 and Confidence Level(95%) value of...

• Replies: 3
• Views: 41,190
07-23-2008, 08:45 AM
18. ### why the sum of residuals must always equal zero?

Hello, I was wondering why the sum of the residuals of a simple regression line must always equal zero. It simply blows my mind that it could...

• Replies: 3
• Views: 40,560
04-26-2011, 11:23 PM
19. ### Low correlation, but significative p-value

Hello, I have a sample n=522, and did a spearman correlation with the result coeffeciente 0,27 **, wich indicates that there isnt a relation....

• Replies: 2
• Views: 40,485
02-02-2011, 08:03 AM
20. ### Scatterplots and Pearson’s r correlation coefficient? #12

O.k. guys. I need a lot of help with these questions. This is a statistics equation that is kicking my butt, and I have no idea how to compute them....

• Replies: 0
• Views: 40,043
08-09-2007, 09:00 AM
21. ### P value interpretation

Hi , I am having a hard time understanding the concept of p value and also its interpretation. I know that I can interpret a p value of 0.80 as...

• Replies: 22
• Views: 39,246
11-28-2011, 02:45 PM
22. ### not significant correlation...

Hi there!!! I am wondering whether you can help me I am not familiar with statistics and I am trying to interpret the outcome of a bivariate...

• Replies: 6
• Views: 38,743
ARI
02-03-2011, 06:58 PM
23. ### mean of means?

Hello, I have run 3 repetitions of the same experiment. Each repetition has over 7000 samples but the number of samples in each repetition not...

• Replies: 2
• Views: 38,449
pjl
04-13-2010, 11:51 AM
24. ### Parsimonious regression model

Hi, I am trying to finish an assignment and I am stumped on one question. It is asking me to build a valid parsimonious regression model. What do...

• Replies: 1
• Views: 38,336
11-02-2005, 09:09 AM
25. ### Cronbach Alpha vs Pearson r

Hi all, this might sound like a completely amateurish question but...what is the practical difference between cronbach's alpha and the Pearson...

• Replies: 25
• Views: 38,028
01-25-2015, 05:51 AM
26. ### moderator vs. mediator variable

I've encountered these terms 100s of times and looked up their definition and tried to understand them at least 15 times. I'm really trying to get...

• Replies: 13
• Views: 37,086
09-06-2012, 11:12 AM
27. ### Reasons for Z-Score standard deviation ≠ 1???

I have a series of 24 raw scores which I have standardized by individually converting them to z-scores. My assignment asks me to calculate the mean...

• Replies: 4
• Views: 36,841
05-09-2008, 04:12 PM
28. ### Standard deviation of the mean difference

Hi, new to the forum, but if anyone can help out with the below query that would be brilliant! I am trying to calculate the Standard Deviation...

• Replies: 1
• Views: 36,773
11-26-2008, 01:21 AM
29. ### Determing Z score from level of confidence

How can I determine the Z score, given a level of confidence of 65%. My math book has the z score for .80, .90, .95, and .99 but none other. ...

• Replies: 1
• Views: 36,762
05-14-2006, 10:03 AM
30. ### Homework help - calculating ρ

Hi everyone, I'm new to the forum and I would really appreciate some help with a homework problem. Sorry about possible language mistakes, my native...

• Replies: 2
• Views: 36,655
04-10-2011, 02:47 PM
31. ### How to interpret a standardized multiple regression coefficient

How can I write an interpretation of the standardized multiple regression equation for both Age of Child and Number of Siblings in this model: ...

• Replies: 4
• Views: 36,629
04-05-2013, 09:34 PM
32. ### significant interaction but non significant simple effects?

Hello everyone, I conducted a 2x2 mixed design ANOVA. The between subjects factor was group (high vs. low), and the within subjects factor was...

• Replies: 13
• Views: 36,376
05-03-2010, 08:27 AM
33. ### Variance of X squared

I have a simple question, but very tricky... I have a random variable Z with: E= S var (Z)= sigma what is var(Z^2)? thanks

• Replies: 5
• Views: 36,365
10-25-2010, 06:36 AM
34. ### Estimate of σ^2 (variance of Y in regression)

Hello, everyone, I have a question about the regression. The textbook said, the mean-square regression term (SSY-SSE) provides an estimate of σ^2...

• Replies: 0
• Views: 36,122
12-07-2012, 11:12 AM
35. ### need help with Case problem:Specialty Toys...pleasseeeee

some1 posted this ? awhile back but never received replies so maybe some1 can help me....ANY help is highly appreciated..heres the problem: ...

• Replies: 5
• Views: 35,994
04-05-2011, 03:48 PM
36. ### Sample size calculation for study with 3 groups

Hi, I need to calculate the sample size for a study comparing 3 groups. I have proportions for 2 of the groups (and can get the 3rd if needed)....

• Replies: 1
• Views: 35,951
08-02-2009, 07:16 AM
37. ### Nonparametric multiple linear regression with SPSS

Is there a way to conduct nonparametric multiple regression analysis using SPSS? If yes, can you provide some explanations on this regard. I...

• Replies: 3
• Views: 35,558
04-30-2012, 02:25 AM
38. ### Which to report with the median - the range or SD?

I have data that is non-normally distributed and I'm writing up my results section. I am trying to figure out whether to include in a table the...

• Replies: 3
• Views: 35,461
05-31-2009, 07:20 AM
39. ### median for grouped data

Guys, that's the last question for tonight, I promise. How to calculate a median and quartiles for grouped data? I have found the following but not...

• Replies: 2
• Views: 35,080
11-02-2008, 10:28 AM
40. ### Mann–Whitney U tests around mean or median?

Hello. So I helped run a fundraising event earlier this year that used an app, and we're now trying to measure if people the used the app...

• Replies: 4
• Views: 34,980
03-05-2013, 11:46 AM
41. ### 5% vs 10% significance level

For hypothesis testing which one is considered stricter 5% significance level or 10% significance level. I know its a very basic question but it...

• Replies: 6
• Views: 34,707
07-21-2012, 03:13 PM
42. ### Scatterplots/ Pearson’s r correlation coefficient & coefficient of determination? #13

O.k. guys. I need a lot of help with this question as well. This is another statistics equation that is kicking my butt, and I have no idea how to...

• Replies: 1
• Views: 34,553
08-10-2007, 09:07 PM
43. ### Standard error - why sqrt of n?

I happened to be browsing through some standard explanations of confidence intervals and came upon the formula for standard error... t x (stddev /...

• Replies: 8
• Views: 34,224
10-15-2008, 09:57 PM
44. ### Comparing two percentages for significance

Hello...this was posted but was lost recently. I am trying to figure out the best method to compare two percentages for significance. I am...

• Replies: 1
• Views: 34,177
04-16-2007, 09:48 AM
45. ### Independent t-test p value 0.000? hmm

What does a p value of 0.00 mean? I know below 0.05 shows significant difference at the 95% confidence level, but I think my teacher is testing us. ...

• Replies: 5
• Views: 34,137
04-07-2009, 07:32 AM
46. ### Probability of correct answers on multiple choice test?

I cannot figure out what formula to use for the following questions. If a student is taking a ten question (four answer choices per question) how do...

• Replies: 1
• Views: 33,839
12-28-2008, 12:11 PM
47. ### Regression analysis with a proportion for the dependent variable

Hi, i want to run a regression analysis for some data I have. The dependent variable is a proportion, and the independent variables are all...

• Replies: 9
• Views: 33,161
04-30-2012, 04:05 AM
48. ### Spearman correlation & Bonferroni test‏

Hello, I would like to ask your opinion about a stat test. I have computed a Spearman correlation between 13 variables (computing two variables at a...

• Replies: 1
• Views: 32,788
11-16-2012, 09:41 AM
49. ### 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: 32,584
01-23-2013, 08:58 AM
50. ### Arcsin transform

Hello, I came across 2 different formulas for arcsin transformation of proportions (0-1) in excel: 1. =ASIN(SQRT(appropriate cell)) 2....

• Replies: 3
• Views: 32,229
01-19-2011, 02:58 PM
51. ### Correlation with a nominal variable?

Hello, I'm conducting a research project where I'm trying to find the correlation between the LSI-R total score (survey) and recidivism (if the...

• Replies: 14
• Views: 32,218
01-21-2015, 08:43 AM
52. ### logistic regression - very high Nagelkerke’s Pseudo-R2 values

Hi all, I have a data set made of 12 years each one with a number of males and a number of females. I tested the relationship between the sex...

• Replies: 5
• Views: 31,948
09-18-2013, 04:15 PM
53. ### Comparing class grades across several courses – is ANOVA appropriate?

Hi all, A group of ~20 students have taken a number of courses, some compulsory and others electives. I want to see whether there is a difference...

• Replies: 3
• Views: 31,442
04-28-2013, 07:02 PM

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