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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: 196,911
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: 66,833
09-30-2005, 09:44 AM
1. ### T test vs. Chi Sq

Is an unpaired t-test the same as a chi sq test with respect to the resulting p-value if I'm using categorical data (0s and 1s)? Thanks.

• Replies: 2
• Views: 1,688
08-20-2013, 01:58 PM
2. ### Best/Most Appropriate method of Analysis?

Hello all, I have a project at work involving ranking and I'm not quite sure how best to proceed or which statistical test/analysis would be best...

• Replies: 5
• Views: 1,676
08-20-2013, 10:52 AM
3. ### One-way ANOVA or two-way ANOVA?

Supposed we gave 100 males and 100 females protein supplement for 3 months. We measured the muscle thickness of the participants before and after the...

• Replies: 11
• Views: 2,505
08-20-2013, 08:11 AM
4. ### can we use ANCOVA in quasi experimental designs?

hi i want to know how check impact of IV on DV. both distributions are extremely non normal and my question is 1. can i trust ANCOVA results to...

• Replies: 4
• Views: 3,465
08-20-2013, 01:28 AM
5. ### Choosing best model in regression - Backwards Stepwise + hierarchical modeling?

Hello - my goal is to fit a model using backwards stepwise regression and hierarchical modeling, testing the association between a primary predictor...

• Replies: 1
• Views: 2,209
08-19-2013, 03:43 PM
6. ### Comaring Logit of full dataset to logit on subset of the dataset

I'm trying to argue that my logit model does a better job of predicting probabilities for a subset of my data than it does for my full dataset. The...

• Replies: 2
• Views: 1,438
08-19-2013, 02:36 PM
7. ### regression to the mean?

Hi, I have a Q regarding regression to the mean. I am doing a within subject design. I am having subjects rate photos of individuals for...

• Replies: 3
• Views: 1,321
08-19-2013, 11:58 AM
8. ### Basic question regarding Logistic regression using census data

Instead of using sampled data, if I use census data to perform Logistic regression, what is the meaning of z-value? Are all coefficients valid...

• Replies: 1
• Views: 1,358
08-19-2013, 09:48 AM
9. ### Question on CHI squared that I don't understand the solution

A experimenter is convinced that her measuring instrument had a variability measured by standard deviation Alpha = 2. During an Experiment she...

• Replies: 0
• Views: 2,987
08-18-2013, 05:51 PM
10. ### Statistics Homework Help

1.) Calculate SS, variance, and standard deviation for the following population of N 7 scores: 8, 1, 4, 3, 5, 3, 4. 2.) A population has a mean...

• Replies: 2
• Views: 8,639
08-18-2013, 05:09 PM
11. ### Conflicting ANOVA & T Test Results. How do I interpret this?

Hey all, I was hoping you could help me with something. I have three data groups, A, B, & C, and I'm testing for a specific effect. I ran a...

• Replies: 6
• Views: 3,046
08-18-2013, 04:23 PM
12. ### state reason for using one tail in the analysis of variance test ?

I think in this way that since in anova we partition the total variability into various independent components , and since the Mean square of this...

• Replies: 6
• Views: 2,177
08-18-2013, 07:20 AM
13. ### 3 Arm Study: Categorical Data needs a P-Value!

Hi, I conducted a 3 arm study and now I am trying to find signficance/lack of signififance. Some data I gathered, such as age was easy to...

• Replies: 3
• Views: 1,475
08-17-2013, 03:11 PM
14. ### Which is the minimum number of replicates that I can use

Hi all, I need to design an experiment but I have a tight budget. Our statistician recommend to have at least 20 df for the error, which most of...

• Replies: 6
• Views: 3,302
08-17-2013, 10:17 AM
15. ### Latent variable interaction

I am trying to fit a model with latent variables interaction. The model is: η3 = β1 η1 + β2 η2 + β3 η1 × η2 + ζ3 in which η2 may be considered...

• Replies: 0
• Views: 1,486
08-17-2013, 06:24 AM
16. ### How to account for short-term trends in time-series data?

Hi guys, I would like to find out which of my 10 independent variables (IVs) best accounts for the changes of my dependent variable (DV) at...

• Replies: 1
• Views: 1,362
08-17-2013, 04:57 AM
17. ### What is model adequacy checking in anova?

In anova, we assume that the random error term \epsilon_{ij} is independent and identically distributed with mean 0 and variance \sigma^2 How can...

• Replies: 0
• Views: 3,695
08-16-2013, 08:03 PM
18. ### Conditional expectation of maximum given minimum of order statistics

Let we have $X_1 ... X_n$ - iid random variables with $F(x)$ - distribution function. So we have $X1:n$ and $Xn:n$ - minimum and maximum. Help me...

• Replies: 1
• Views: 3,140
08-16-2013, 09:18 AM
19. ### Interpreting sensitivity and specificity with corresponding PPV and NPV

Hello, I have calculated sensitivities, specificities with pos and neg predictive values for different cutoff values of two biomarkers. What i...

• Replies: 9
• Views: 3,528
08-15-2013, 02:43 PM
20. ### 3 columns of categorical data - what test to use for significance?

Hi I did surveys on pre-teens, teens, 20s (3 "columns") and need to find signfifiance (p-value). What test do I use? I keep trying Chi square on...

• Replies: 4
• Views: 2,503
08-15-2013, 12:33 PM
21. ### Sobel mediation test with a categorical IV (3 variables) - help appreciated

Hello, Sorry this is probably a simple question - I know how to do a sobel test with a categorical IV with 2 categories but am unsure if there...

• Replies: 0
• Views: 1,844
08-15-2013, 08:34 AM
22. ### Accounting for confidence intervals in determining a mean

I have received some elemental analysis of a metal which I want to use to determine the effects of radiation. I want to report my results for the...

• Replies: 0
• Views: 2,236
08-15-2013, 07:28 AM
23. ### Comparing groups - Normalization to control

Hello everyone! This is my first time around. I know a few things about classical hypothesis testing, p values and CIs, but beyond that, my...

• Replies: 0
• Views: 5,158
08-15-2013, 02:48 AM
24. ### Linear Mixed Model vs Nested Design for Behavioral Data

I am relatively new to statistics and was wondering if someone could help me determine which test to use to analyze my data. I am testing behavioral...

• Replies: 0
• Views: 1,744
08-14-2013, 04:16 PM
25. ### What is the pdf of the standard deviations of a set of gaussian distributions?

Hi all, I'm analysing some data from an oceanographic experiment and looking for some statistical widsom. We have a set of profiles of the...

• Replies: 0
• Views: 1,987
08-14-2013, 06:44 AM
26. ### MNL model using Nlogit: Flat log-likelihood

Hi there I have collected data from a Choice Modeling survey, and I am having a few problems assessing the outputs when using an MNL model through...

• Replies: 0
• Views: 1,499
08-14-2013, 06:10 AM
27. ### Help reporting stats with a graph

Hey everyone I'm a university student and I'm looking to report some statistics about a medical intervention for a review that I'm doing. The...

• Replies: 0
• Views: 1,116
08-14-2013, 04:40 AM
28. ### Bayes CFA

Hi Folks, I have several questions about Bayes CFA in Open bugs that I hope you might be able to help me out with. First the setup: Here is a...

• Replies: 5
• Views: 4,309
08-14-2013, 12:19 AM
29. ### Correlation analyses in Excel/SPSS

Hi there, Could someone help me with conducting some correlation analyses in Excel/SPSS? I already set up an Excel document in which I made some...

• Replies: 0
• Views: 1,577
08-13-2013, 05:33 PM
30. ### overdispersion of binary data

Hi, I have binary data that I am testing for the significance of nesting effects. How do I determine if (or whether) the data is overdispersed?...

• Replies: 7
• Views: 4,658
08-13-2013, 03:33 PM
31. ### Which test to use?

Hi, 1. I need to know how to compare CATEGORICAL DATA. I have 4 types of anesthesia applied to 3 different groups (a, b, c). What test do I use to...

• Replies: 2
• Views: 1,896
08-13-2013, 11:33 AM
32. ### Which statistical test when comparing two groups to see which is closer to control?

To elaborate, I have 3 groups for a study. They each have log ratios for the same set of 5522 sample data. Group A Group B ...

• Replies: 1
• Views: 2,093
08-13-2013, 10:42 AM
33. ### Can I use Chi-Squared Likelihood Ratio?

Hello Everyone! This forum looks great and thank you to any kind people willing to help me out. Probably a simple question, but I cannot find...

• Replies: 1
• Views: 2,678
08-13-2013, 10:04 AM
34. ### Detecting outliers in preparation for CFA and SEM

I plan to do CFA and SEM involving about 6 latent variables, each measured with 3 or more indicators (all measured with a 7-point Likert scale). ...

• Replies: 0
• Views: 2,360
08-13-2013, 09:16 AM
35. ### Distribution of averages in non-parametric stats??

Hi, I am new to the forum and learning the stats I need as I go:) I have done some parametric stats in undergrad but never dealt with...

• Replies: 1
• Views: 1,673
BGM
08-13-2013, 07:31 AM
36. ### how to classify.mean score for.3 point likert scale?

Hey everyone i am now in great need for help. I actually did a questionnaire with 3 points of likert scale which are not agree, not sure, and agree....

• Replies: 2
• Views: 2,217
08-13-2013, 02:41 AM
37. ### Use of dummy in Plackett-Burmann screening

I am trying to set up an experiment for optimizing medium composition for bacterial growth using the Plackett-Burman design. I am planning to do a...

• Replies: 8
• Views: 5,091
08-13-2013, 12:55 AM
38. ### Comparing groups with different sample sizes. ANOVA?

Hi guys, I am trying to figure out if there is a statitcal difference between the average number of infant deaths between low, med, and high income...

• Replies: 5
• Views: 2,190
08-12-2013, 07:18 PM
39. ### Margin of error for stratified survey sample

Hi all, apologies for cross-posting: I posted this in another forum last week; it received over 100 views but no responses! I have a stratified...

• Replies: 3
• Views: 6,187
08-12-2013, 07:11 PM
40. ### Sorry - another question on normality and ANOVAs - sources needed ....

Hello everyone, I have been trying to find information everywhere and would be so grateful for any help. My situation: As part of my postdoc...

• Replies: 7
• Views: 1,979
08-12-2013, 06:30 PM
41. ### Compare four groups of (related???) data -- is a Friedman test ok?

Hello, During my study of animal behavior, each of my 10 study subjects (all young females) received a number of aggressions from individuals...

• Replies: 0
• Views: 1,569
08-12-2013, 06:04 PM
42. ### Which statistical test to use for significance (p-value)?

Hi, I am trying to find significance in a study I conducted. There are 3 groups (so 3 columns on MS Excel) and I am testing significance between...

• Replies: 3
• Views: 1,848
08-12-2013, 04:03 PM
43. ### Mean and variance of multiplication of several random variables

Hi, Can anybody help me to know how I can calculate the mean and standards deviation of several random variables multiplication? Z=x1.x2...xn while...

• Replies: 0
• Views: 1,432
08-12-2013, 03:49 PM
44. ### Group Size for Binary Logistic Regression

I am trying to determine the odds ratio for the effect of C on A. However, my is a sample of n = 45 with 4 = yes and 41 = no. Is this small group...

• Replies: 6
• Views: 2,103
08-12-2013, 02:44 PM
45. ### Statistical Analysis: Which measure of association for me?

My research hypothesis claims that there is a relationship between my independent variable, student’s economic status and the dependent variable, SOL...

• Replies: 1
• Views: 1,492
08-12-2013, 01:56 PM
46. ### Logistic Regression Problem

Hi I was reviewing some old logistic regression material. I saw where one document referred to the logit as linear regression. Therefore, this...

• Replies: 6
• Views: 1,680
08-12-2013, 01:40 PM
47. ### Variance Components and Intraclass Correlation Coefficients for Binary Data

Hi, I am performing a variance components analysis of a 3 level nested model of binary data. Given the lack of homoscedasticity at the individual...

• Replies: 0
• Views: 1,715
08-12-2013, 12:59 PM
48. ### Exponential Distribution Question

Can someone please help me with the attached question? I'm stuck on it for so long and it's driving me crazy, I think it's relatively easy but I...

• Replies: 2
• Views: 2,517
08-12-2013, 12:52 PM
49. ### How many pp do I need to know my correlation applies to the larger group?

How many pp do I need to know my correlation applies to the larger group? I'm looking a people in a few prisons and what economic backgrounds they...

• Replies: 4
• Views: 3,055
08-12-2013, 07:13 AM
50. ### Quartiles in a normal Distribution

how would one find quartiles in a normal distrubtion? im just confused as to what im supposed to look for i know the mean/median/q2 in this case...

• Replies: 5
• Views: 124,397
08-12-2013, 04:39 AM
51. ### Stochastic Model Validation

Hi, I am working on a model that takes in a stochastic time series (turbulent velocity) as input and produces n time series outputs. Since the inputs...

• Replies: 0
• Views: 2,641
08-12-2013, 03:42 AM
52. ### Chi-square post-hoc tests - Adjusted residuals vs. 2x2 chi-squares.

Hi, I'm running a few chi-square analyses that are greater than 2x2 tables and am interested in reporting exactly where the significant...

• Replies: 1
• Views: 5,620
08-12-2013, 01:21 AM
53. ### P-Value/ Z statistic

Hi! I've posted a question and have attempted some of them. If someone could please help me get started or provide an explanation to what to do to...

• Replies: 0
• Views: 4,290
08-11-2013, 04:51 PM
54. ### independent t tests

If I have 2 independent groups and need to determine the significant difference in scores between the 2 groups where Ho(u2-u2)+0 no difference and...

• Replies: 3
• Views: 1,585
08-11-2013, 04:01 PM
55. ### Sample Size

Hi, I hope this is not a silly question, I have been through the forum posts and a few text books, but I have got myself confused. The problem is...

• Replies: 3
• Views: 2,047
08-11-2013, 12:40 PM
56. ### Comparing means subgroups in SPSS

Hello I would really appreciate some help with a problem I have in analysing my data. I am using SPSS 21 and would like to compare cell counts...

• Replies: 0
• Views: 3,689
08-11-2013, 06:03 AM
57. ### Can anyone help me with these questions?

• Replies: 1
• Views: 2,068
08-10-2013, 07:48 PM
58. ### 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: 2,760
08-10-2013, 03:36 PM

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