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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: 196,608
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: 66,642
09-30-2005, 09:44 AM
1. ### 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: 2,571
10-04-2012, 12:24 PM
2. ### Using Cox multivariant regression!

Hi I am trying to do Cox multivariate regression analysis in a project where I am trying to identify predictors of a particular disease using...

• Replies: 0
• Views: 1,901
10-04-2012, 11:10 AM
3. ### Two Questions

First, I am trying to test two samples that have an extreme right skew against each other to figure out if there is a difference between the means. I...

• Replies: 1
• Views: 1,110
10-04-2012, 10:56 AM
4. ### Thought this was a simple linear regression, but now confused ...

Hi: For practice (and of some use) I did a simple linear regression as follows (using one test subject for 90 days): the predictor was milligrams of...

• Replies: 0
• Views: 1,210
10-04-2012, 09:53 AM
5. ### Testing for correlation between a continuous variable and a categorical outcome

Hi, I was wondering if anyone could help. I am trying to test for correlation between a continuous variable (patients' symptom interval, measured...

• Replies: 4
• Views: 2,525
10-04-2012, 09:01 AM
6. ### Testing for two means

I am doing practice questions for hypothesis testing, for two means, n is large. I know the test stat for two means. H0: Mu1 - Mu2 = 0, Ha: Mu1...

• Replies: 5
• Views: 1,578
10-04-2012, 04:06 AM
7. ### How would ANOVA F-test change when you are testing equal means for subset of group?

Suppose I had an independent random variable with Y_ij distributed N(miu_i, sigma) where miu_i and sigma are unknown. Now, 1<= i <= 5 and 1<= j <=...

• Replies: 1
• Views: 1,451
10-04-2012, 01:46 AM
8. ### Trying to display 3+ scaled variables in one table

Hello, I've been trying to display 3 variables that use the same scale with the same value labels in one table in SPSS V19 and have been...

• Replies: 1
• Views: 1,227
10-03-2012, 08:40 PM
9. ### Stat & probability word problems

I need help on 3 homework problems @ least get an idea as to how to go about solving them. Question 1: Tom works the night shift at a gas station...

• Replies: 2
• Views: 3,698
10-03-2012, 07:28 PM
10. ### Cross Validation/Bootstrap on Time Series Segement

I have a small time series segment (~100 to ~500 points) and would like to fit a function to it. I'm not interested in the out of sample performance,...

• Replies: 3
• Views: 1,759
10-03-2012, 01:59 PM
11. ### bottling plant problem

Problem. A company has given a contract to a bottling plant to fill its products with the product. The company has specified to the bottling plant...

• Replies: 1
• Views: 1,309
10-03-2012, 01:19 AM
12. ### Calculating correlation between dichotomous data and interval data?

Hi, I'm hoping that someone might be able to point me in the right direction with this... I'm a respiratory physiotherapist working on my...

• Replies: 1
• Views: 1,631
10-02-2012, 04:02 PM
13. ### discrete choice model in r with mlogit with nested data

My data has multiple observations within participants. Each participant has 10 trials. For each trial, there are 4 options, there are variables...

• Replies: 1
• Views: 1,309
10-02-2012, 03:59 PM
14. ### How can a PDF produce values larger than 1?

I'm looking for an intuitive explanation on how a PDF can produce values larger than 1. To my understanding, a probability density function is the...

• Replies: 3
• Views: 1,454
10-02-2012, 01:14 PM
15. ### From significance to insignificance. How come?

Hi Guys, I am doing a research and i am struggling with one problem. Iam performing a logit regression. I have several variables, but one...

• Replies: 0
• Views: 915
10-02-2012, 05:04 AM
16. ### Random vs. fixed effects: explain it to grandma rinker

Let's start by role playing; I'm your grandma and I know nothing or very little about stats. I've been hearing about fixed and random effects (not...

• Replies: 1
• Views: 1,889
10-01-2012, 11:29 PM
17. ### finding a tutor for SPSS?

Sorry if this is in the wrong section, I'd like to find an online tutor who can help me with producing SPSS outputs for a few lab reports that I'm...

• Replies: 2
• Views: 1,440
10-01-2012, 06:34 PM
18. ### Multiple Regression Model To Predict Comments Based on Referrers

I want to predict the comments on a blog post based on the referrers the blog post received. I've already gathered up the data, put it into R, and...

• Replies: 0
• Views: 1,054
10-01-2012, 06:24 PM
19. ### intro stats: statistical assumptions?

hello! hoping someone can help me. our class did a small sampling project. we had to count how may people wear hats to class on monday's vs...

• Replies: 2
• Views: 2,108
10-01-2012, 03:23 PM
20. ### Appropriate to use time as covariable in ANCOVA?

Hello stats people, I need to assess whether the rate of increase (in soil carbon) differs significantly between two groups (forests). I believe...

• Replies: 11
• Views: 2,888
09-30-2012, 10:50 PM
21. ### central limit theorem and mean

Hi, I know that the central limit theorem states that as sample size increases the sampling distribution of the sample mean tends toward normal....

• Replies: 8
• Views: 1,998
09-30-2012, 04:28 PM
22. ### How best to account for seasonality when analysing bird monitoring data

Hello All, I have some monitoring data from seabird surveys carried out in an offshore construction site. Surveys were undertaken before, during...

• Replies: 1
• Views: 1,585
09-30-2012, 01:43 AM

Research data indicates that adolescents, especially adolescent girls, experience a drop in self-esteem. To evaluate this result, a researcher...

• Replies: 0
• Views: 1,657
09-29-2012, 09:31 PM
24. ### Help on Ratio

Can anyone help me? For example, I have a store, 4 people bought iPhones and each buyer bought accessories too. Buyer#1: 1 iPhone, 4...

• Replies: 2
• Views: 2,304
09-28-2012, 08:37 PM
25. ### Help choosing tests

Hi All, I am needing some advice with regards to choosing an approriate test for some data that I will be researching. Basically participants...

• Replies: 2
• Views: 1,516
09-28-2012, 08:58 AM
26. ### Regarding supremum

Hi guys, I hope everyone's been doing well. I have a quick question. Figured someone could answer without much effort. I know that with...

• Replies: 9
• Views: 1,875
09-28-2012, 12:45 AM
27. ### Linear regression & correlation for time series data

Hi all, I've searched wide and can only find warnings about NOT applying common linear regression and correlation statistics to time series data,...

• Replies: 2
• Views: 1,698
09-27-2012, 10:52 PM
28. ### how to solve this problem ?

A new procedure is carried out in order to reduce the radiation exposure to the technologists during the examination for the patients. The radiation...

• Replies: 1
• Views: 1,052
09-27-2012, 04:50 PM
29. ### Is it allowed to take the standard deviation of percents?

Hello, I've a data set of 1002 (I'm quite sure it is not a normal distribution). Foreach entry i've some Value in %. I've calculated the mean...

• Replies: 2
• Views: 2,862
09-27-2012, 01:41 PM
30. ### Favorite beginner textbook?

Sorry if this is repeat info; I am a newbie to the Forum. I did a quick search and did not see a similar question, so here goes: I am teaching a...

• Replies: 8
• Views: 1,726
09-27-2012, 12:54 PM
31. ### General Question: What is the meaning of an + or - sign as exponent?

I don't know whether this is the right place for the thread. Nevertheless I am interested in the meaning of a plus or minus sign in the exponent. Can...

• Replies: 5
• Views: 1,508
09-27-2012, 07:53 AM
32. ### Interpreting Confidence Intervals

Hey everyone. I am trying to answer a question on my homework. If the confidence intervals are both negative (i.e. the lower and upper bound) then do...

• Replies: 7
• Views: 3,793
09-26-2012, 08:29 PM
33. ### Mean of means, Error Bars and Pooled Variance

Hello, I am conducting an experiment and I am having a problem with the statistics. The most important analysis is basic stuff and it's done but...

• Replies: 1
• Views: 1,810
srd
09-26-2012, 10:29 AM
34. ### Can't figure out what test to use.

Hello, I have tried all kinds of test in spss in order to find out if there are any significant difference in compliance between different citys....

• Replies: 6
• Views: 1,842
09-26-2012, 09:22 AM
35. ### Probability of Sample Mean

I am stuck at this question for a test, According to a survey it takes 0.7 seconds to download the home page of a website. Suppose that the...

• Replies: 3
• Views: 4,788
09-26-2012, 07:45 AM
36. ### Difference of 2 Chi-Square Variables Still a Chi-Square Variable?

I did a problem for homework that made me show that the sum of two chi-square variables is still a chi-square variable. However, when I find the...

• Replies: 2
• Views: 1,885
09-25-2012, 09:52 PM
37. ### equal variance fails

Hello, Well, I can assure you, I have read up on this particular issue. In principle, I should be doing a 3-way RM anova but sigma stat does not...

• Replies: 0
• Views: 1,487
09-25-2012, 09:48 PM
38. ### [Relation of daily sales] Chi-Square, T-Test or Correlation?

Hello, Which to use to test whether Monday sales and sales on the other days of the week are independent from each other. Case: A promotion...

• Replies: 8
• Views: 1,463
mba
09-25-2012, 08:26 PM
39. ### Log normal distribution.

Hello all, I was going through the posts on this forum to solve at least one of the queries and it seems like I am an amateur at stats so this...

• Replies: 3
• Views: 1,536
09-25-2012, 11:02 AM
40. ### 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

Hello, I would very much like to find out what test to use for the following data. I have percentage of compliance (how many people who...

• Replies: 2
• Views: 1,184
09-25-2012, 02:14 AM
42. ### confidence levels and t tests

A florist wants to know if the orchids have a greater impact on the design asthetics of a room, when they are potted in a large pot rather than a...

• Replies: 5
• Views: 2,106
09-24-2012, 08:02 PM
43. ### Correlation Question w 3 variables

Can someone please tell me how it is possible for X to be correlated with Y and Z to be correlated with Y, but X and Z be uncorrelated? I'm having...

• Replies: 7
• Views: 2,280
09-24-2012, 06:10 PM
44. ### Overlapping Standard Deviations

Hi, I have some data from an experiment that has one factor (temperatures) and five levels. When I plot the data with the standard deviations...

• Replies: 3
• Views: 5,872
09-24-2012, 04:34 PM
45. ### Poisson Random Distribution

Hello, I haven't had any statistics in over 10 years, and gotta say that I'm having a hard time getting into it. I'm currently working on an...

• Replies: 1
• Views: 943
09-24-2012, 03:47 PM
46. ### independent or paried t test?

the Census bureue believe that recently the ethnic composotion of a certain city has changed. 5 years ago there were 40% Asian, 22% Caucasian, 8% AA,...

• Replies: 8
• Views: 2,239
nyo
09-24-2012, 01:05 PM
47. ### Fisher's Exact Test for determining correlation between variables

Hello all, My P.I. has presented me with a 2x2 contingency table and asked me to perform Fisher's Exact Test to determine whether a correlation...

• Replies: 14
• Views: 14,552
09-24-2012, 11:52 AM
48. ### variability around a set of integers

Hi. Say I have 100 observations for 10 variables. Each observation for each variable should ideally be coded as 1,2 or 3. However, it is possible...

• Replies: 1
• Views: 1,734
09-24-2012, 07:47 AM
49. ### Minimum sample size for paired t-tests

Hi All, I remember reading somewhere that the minimum sample size to conduct paired t-tests was ~30, as this will ensure that there is adequate...

• Replies: 7
• Views: 19,641
09-23-2012, 12:48 AM
50. ### repeated mesures with negative correlation

Hi all I'm a data analyst at the University of Sydney, Australia doing research into home advantage in soccer. I am using Poisson regression to...

• Replies: 0
• Views: 2,019
09-22-2012, 10:01 PM
51. ### Summation Problem - new in the forum

Hello everyone, I am new in the forum and I came here because I am desperate. I am taking stats 1101 in school not because I chose to, but because I...

• Replies: 3
• Views: 1,562
09-22-2012, 03:36 PM
52. ### Quick IV/DV Question

Hi everyone, Ive got a quick question on variable types. In my study, people watch a clip, then answer how they feel between 1 and 10. Then they...

• Replies: 0
• Views: 1,273
09-22-2012, 01:15 PM
53. ### R question

Any suggestions to find a formula relating R-square and the F-test for regression.

• Replies: 7
• Views: 3,063
09-22-2012, 09:21 AM
54. ### Error Propagation

If I have two sets of measurements (x and y) each with 3 values x: 1,2,3 and y: 4,5,6 and I need to divide the two x/y to get z can I work out all...

• Replies: 0
• Views: 1,047
09-21-2012, 08:57 PM
55. ### Post Hoc testing for ANCOVA

Hi everyone. I am trying to figure out what post hoc tests are most appropriate for an ANCOVA with two IVs and two Covariates where one IV may act as...

• Replies: 0
• Views: 1,181
09-21-2012, 04:26 PM
56. ### Likert scale data and regression

First I know that in theory the independent variables don't assume any given distribution. But in fact that can't be true or you would use...

• Replies: 16
• Views: 5,380
09-21-2012, 04:11 PM

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