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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: 197,111
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: 66,929
09-30-2005, 09:44 AM
1. ### testing a null hypothesis that is a range

My text shows how to do hypothesis testing given a significance level and a null hypothesis, but on my assignment I'm required to test a null...

• Replies: 3
• Views: 2,651
10-01-2013, 02:01 PM
2. ### Expected value (mean)

Hi All I'm looking for a metric that shows a close trend (good correlation) to the mean (expected value) of a distribution, so I can investigate...

• Replies: 6
• Views: 1,437
10-01-2013, 10:53 AM
3. ### Standard Deviation of Half distribution

Hi, Recently I heard about calculating Standard Deviation of the upper half of a distribution which raised my eyebrows. Is this really...

• Replies: 1
• Views: 3,035
BGM
10-01-2013, 06:45 AM
4. ### Hypothesis Testing

You arrive late at a race track; the cars are already hurtling past you. You know from past experience that the cars are numbered (and labeled) 1,...

• Replies: 0
• Views: 1,093
10-01-2013, 05:45 AM
5. ### Coin flipping

Alan, Bob, and Charlie agreed that the “odd man” (the person whose outcome is different from others) would buy the coffee. After simultaneously...

• Replies: 0
• Views: 1,012
10-01-2013, 05:23 AM
6. ### test for ratios

Hi. I'm conducting a research concerning forecasting exchange rates. I compare several models, currencies and time horizons. All models are compared...

• Replies: 1
• Views: 2,333
09-30-2013, 08:56 AM
7. ### Can you give me some references?

I need the derivation of the parameters of distributions including: Gumbel, Weibal, Lognormal and Gamma with both method of moments and maximum...

• Replies: 1
• Views: 1,221
BGM
09-30-2013, 08:52 AM
8. ### How to interpret and compare models in Cox regression?

Hallo, I am trying to interpret the results of a Cox regression; I am doing a PhD in medicine. I love statistics but my question is still pretty...

• Replies: 0
• Views: 1,707
09-30-2013, 07:13 AM
9. ### Address whether one overlap is significantly bigger that of another related overlap

I could really use a hit as to which statistical test I need to use to address the following problem: I have three different species: A, B and C....

• Replies: 0
• Views: 1,701
09-30-2013, 06:25 AM
10. ### Percentage Points

Hello all I wanted to ask you something about percentages. I have a variable X, which is the change of some measure in %. I have calculated X's...

• Replies: 0
• Views: 1,441
09-30-2013, 01:49 AM
11. ### Finding value representing the indicated percentiles help!

Hi, I am having some issues solving this problem involving stock prices for indicated percentiles. Use the following set of stock prices (in...

• Replies: 0
• Views: 1,856
09-29-2013, 11:07 PM
12. ### Ambiguous question in homework...

Hi All, I just wanted to probe this board before I went to the TA, as class just started and I don't want to be *that* guy. Anyway, I have an...

• Replies: 0
• Views: 1,976
09-28-2013, 04:43 PM
13. ### Descriptive Statstics Question!!

Hey guys, I need your help: I got following question: Six customers have Tested a new chocolate bar an have rated it on 0-10 scale...

• Replies: 0
• Views: 988
09-28-2013, 10:03 AM
14. ### Effect Sizes question

Hi all, I have two different samples, and need to know if there are differences in the means. Sample 1 has 46 people in it. It has a Mean of...

• Replies: 5
• Views: 1,784
09-27-2013, 03:23 PM
15. ### Questions about Contrasts in a 3-way ANOVA related to error terms and t-tests

A friend and I are trying to determine the most appropriate way to analyze some data that we have. Our Design is a 2x2x2 between Subjects design,...

• Replies: 0
• Views: 1,088
09-27-2013, 01:57 PM
16. ### Use of moderating variable in hypothesized model

i have constructed a hypothesized model in which two independent variables; these are 1.potential 2. future prosepects. Independent variable i-e...

• Replies: 1
• Views: 1,090
09-27-2013, 01:25 PM
17. ### Sample mean: bias and variance

I am having a bit of difficulty with the following questions: My attempts at answering the problems: 1. I believe that this process could...

• Replies: 0
• Views: 1,106
09-27-2013, 10:50 AM
18. ### Population size question

Let me first say I am not well versed in statistics, but I cannot seem to find the asnwer to my question by doing a Google Search (perhaps I am not...

• Replies: 2
• Views: 1,234
09-26-2013, 07:11 PM
19. ### Concept of P value

Hi Guys Recently I started working towards improving my understanding of basic concepts of statistics and have read a few posts/books online about...

• Replies: 19
• Views: 7,055
09-26-2013, 06:51 PM
20. ### Is ANCOVA being used correctly?

Hi! I am having a serious horrible time with an ANCOVA issue, and I would be immensely grateful for any help. I am writing an evaluation of a...

• Replies: 1
• Views: 1,306
09-26-2013, 02:06 PM
21. ### Confidence intervals for difference between Poisson rates

Hi, My data consists of occurrences of words in time windows. E.g.: Day; Word; Frequency 1; "dog"; 45 1; "cat"; 2 ... 2; "dog"; 90 2; "cat";...

• Replies: 0
• Views: 1,207
09-26-2013, 10:10 AM
22. ### Log-rank or Wilcoxon test

I want to compare two survival curves (cumulative) and I’m not completely sure which of the two tests is most appropriated log-rank or wilcoxon test....

• Replies: 2
• Views: 2,285
09-26-2013, 07:58 AM
23. ### 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: 1,534
09-25-2013, 03:23 PM
24. ### Quick Tips?

If my Hypothesis is Mean BMI is equal for all three teams... What test should i use? 1 way ANOVA? What test can i perform to determine which...

• Replies: 0
• Views: 1,255
09-25-2013, 01:22 PM
25. ### Presenting the results: Continuous variables, Normally distributed vs non normally

Hi :) My question is most probably simple but I can't find an answer to it. According to my stats textbook one should report continuous...

• Replies: 2
• Views: 4,193
09-25-2013, 10:19 AM
26. ### Missing Data - Comparing Methods

Firstly, I hope I make sense... I am working on an assignment that involves comparing different methods of dealing with missing data (e.g. EM, mean...

• Replies: 0
• Views: 1,028
09-25-2013, 05:27 AM
27. ### Improved Monte-Carlo method vs. hit-and-miss method

I am not understanding *Which is more accurate, the hit-and-miss method or the improved Monte-Carlo method?* ...

• Replies: 0
• Views: 2,838
09-25-2013, 03:17 AM
28. ### resources for learning how to work with expectation

I'm doing a course in econometrics I have to do lots of expectations, but I have never been taught how to do them. Is there a resource that...

• Replies: 3
• Views: 1,283
09-24-2013, 06:37 PM
29. ### Help with Volatility and Standard deviation predictions for football stats

I really have just trying to create a excel to help me with my fantasy football. I would love to talk with a mathematician on skype for a few mins to...

• Replies: 0
• Views: 1,026
09-24-2013, 03:47 PM
30. ### Correlational statistics such as pearson product moment and regression analysis

Reading through previous threads I fear my question will sound very basic in comparison! I am currently researching the appropriate statistical tools...

• Replies: 1
• Views: 1,055
09-24-2013, 03:03 PM
31. ### Factor Analysis

Hello! I run a Factor Analysis and got 14 factors with an Eigenvalue above 1! The first 5 factors explain most of the variance (Eigenvalue >2)...

• Replies: 2
• Views: 1,410
09-24-2013, 12:24 PM
32. ### Histogram help

Hi, I have an exam in two days and I need help with these 3 problems. I know the answers but I don't know they got them. Can you please explain to me...

• Replies: 0
• Views: 984
09-24-2013, 10:20 AM
33. ### Bivariate normal distribution

Hi guys, I am really a layman in statistics. Recently I have the problem related to the bivariate normal distribution. Assume that I have the...

• Replies: 0
• Views: 1,314
09-23-2013, 06:44 PM
34. ### ancova

Hello, I have a set of data (Xi,Yi) to which I fit a curve: Y=a*X^b, I use matlab to determine a and b. I also have a model equation: Y=a0*X^b0....

• Replies: 0
• Views: 1,129
09-23-2013, 05:41 PM
35. ### Congruential Generators.

Find all of the cycles of the following congruential generators. For each cycle identify which seeds X_0 lead to that cycle. (a). X_{n+1} = 9X_n +...

• Replies: 1
• Views: 1,093
09-23-2013, 08:17 AM

I am interested in conducting a quasi-experimental study, due to the lack of true randomization in selecting the control and treatment groups. School...

• Replies: 3
• Views: 1,496
09-23-2013, 07:53 AM
37. ### Violation of Normality Assumption in Mixed Design ANOVA

I conducted a study in which two groups of teachers (pre-service and veteran) all watched four video clips of instances of aggression between...

• Replies: 0
• Views: 1,774
09-22-2013, 09:51 PM
38. ### Z score

Hi guys I need help with this question: Past data indicates an 80% success rate in treating a certain medical problem. A new treatment is used on 100...

• Replies: 1
• Views: 2,166
09-21-2013, 09:22 AM
39. ### Covariance matrix - understanding the meaning

Hey guys. Please consider the covariance matrix M = . Now consider a gaussian 3 dimensional plot: z = C1 * e^(-C2 * M * t) = C1 * e^(-C2 * ) ...

• Replies: 1
• Views: 1,895
BGM
09-20-2013, 11:44 AM
40. ### fit a histogram

Say we have a vector data<-c(5,2,46,49,10,68,65,34,75,60,57,18,45,5,1,4,28) hist(data) We want to fit the histogram with a normal distr....

• Replies: 3
• Views: 1,297
ole
09-20-2013, 09:24 AM
41. ### Generating Random Investment Returns assuming a Student's T Distribution

Hi there I'm new to Talk Stats so forgive me if I'm doing something wrong. I need some help in building a random number generator in excel...

• Replies: 1
• Views: 1,564
BGM
09-20-2013, 07:14 AM
42. ### Question on methodology concerning categorical variables with repeated measures

Hello, I have a dataset which includes the following data: It contains information on how frequent specific medications have been prescribed over...

• Replies: 2
• Views: 1,517
09-19-2013, 11:43 PM
43. ### 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: 2,077
09-19-2013, 08:01 PM
44. ### Is weighted average the best?

Hi Stats for absolute beginners! I have four different gradients on a piece of land of 1,000 square yards. 50% is a 1% gradient 20% is a 2%...

• Replies: 1
• Views: 1,062
09-19-2013, 06:21 PM
45. ### Dose-response meta analysis

my professor gave data set of 3 studies investing the effect of a serum concentration of a drug on the a disease outcome study dose ...

• Replies: 0
• Views: 967
09-19-2013, 05:50 PM
46. ### Which test to perform and how?

I would like to do a statistical test and I'm not sure which is appropriate. I have data reflecting different time durations (6 to 12 minutes) and...

• Replies: 0
• Views: 899
09-19-2013, 02:28 PM
47. ### Which statistical test to compare population percentage change over time?

Hi, I'm relatively inexperienced with statistical tests and I'm trying to figure out which test to use for the following: I am comparing three sets...

• Replies: 1
• Views: 4,921
09-19-2013, 01:54 PM
48. ### How to proceed analysing survey data

Dear All, I am new to survey analysis and trying to analyse some survey data based on individual and their knowledge on their local leaders. I have...

• Replies: 1
• Views: 1,115
09-19-2013, 01:43 PM
49. ### Sample size calculation issues

Hello, I have a question regarding a research project I'm working on. We have conducted an experiment where the same sample is measured over and...

• Replies: 1
• Views: 1,760
09-19-2013, 01:34 PM
50. ### Sampling error and non-sampling error

I am extremely confused as to what the difference between a sampling error and a non-sampling error is. Can someone please explain?

• Replies: 3
• Views: 974
09-19-2013, 01:12 PM
51. ### Nonparametric Mann-Whitney U for 4 groups

I have been trialling the effectiveness of a drug on brain injury and have treatment groups: 1) Control + drug 2) Control + vehicle 3) Injured +...

• Replies: 2
• Views: 1,396
09-19-2013, 03:37 AM
52. ### Intervention vs. Control Group for Matched Pair, dichotomous data: McNemar Test?

I have matched-pair, pass/fail data on a reading test for 2010 and 2012. I have this for an intervention group and a control group of students. I'm...

• Replies: 2
• Views: 3,893
09-18-2013, 06:09 PM
53. ### Two-Way ANOVA

Please disregard previous post, it just shows how messed up I am!!!:) My problem is: A two-way ANOVA shows significant interaction, but both...

• Replies: 2
• Views: 2,080
09-18-2013, 04:51 PM
54. ### 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: 31,974
09-18-2013, 04:15 PM
55. ### Manipulating the X and Y Values within the regression data

Assume that least-squares estimates are obtained for the relationship Y=a+bX. After the work is completed it is decided to multiply the units of the...

• Replies: 0
• Views: 850
09-18-2013, 10:09 AM
56. ### Trying to find the correlation for 2 variable when controlling for 2 other variables

I summed up some of the info we are already provided: N=50 Having job and exam performance--- r= -.3 Having job and and Studying--- r= -.4...

• Replies: 0
• Views: 1,534
09-18-2013, 10:02 AM

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