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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: 197,168
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: 66,955
09-30-2005, 09:44 AM
1. ### Write Likelihood function

HOw to write likelihood and log-likelihood of this bivariate distribution? Thank You! $Y|X = x ~ N(0,\lambdax^2)$ $X ~ N(0,\sigma^2)$ con ...

• Replies: 1
• Views: 1,304
05-13-2015, 07:45 PM
2. ### How would I compare two samples with independent variables not using a t-test?

Hi Guys This is my first post, and I am not fantastic with stats so please stick with me. Is there a way that I can statistically say if two...

• Replies: 2
• Views: 1,164
05-13-2015, 01:48 PM
3. ### Combining standard deviation of percentages

I have a sample set for which I've determined the percent inhibition (1 - test sample / control sample). There is error inherent with each sample set...

• Replies: 0
• Views: 1,559
05-13-2015, 11:21 AM
4. ### optimum number of strata in cox regression

Hi all, Is there any advice on the maximum number of strata for a stratified cox regression ? In a study I have to analyze, the total sample...

• Replies: 7
• Views: 1,578
05-13-2015, 10:49 AM
5. ### Medical Statistics: Comparison of diagnostic accuracy studies

Hello: I require assistance I have a population of patients undergoing two different diagnostic tests. I have already tabulated the...

• Replies: 6
• Views: 1,759
05-13-2015, 10:36 AM
6. ### Comparison of large dataset

Dear statisticians, I have ran an experiment which gave me information about the fluorescence intensity of 10.000 cells. I have repeated the...

• Replies: 0
• Views: 1,042
05-13-2015, 04:37 AM
7. ### How to compare size distributions between 3 areas

I'm trying to figure out the best test to compare size distributions of crabs caught in three different areas. I binned the data in size classes...

• Replies: 2
• Views: 1,198
05-13-2015, 02:55 AM
8. ### Irregular Time Series Analysis

How to analyse a irregular time series? Should I convert it to a regular time series? I have daily prices of a product. But the prices are not...

• Replies: 0
• Views: 2,048
05-12-2015, 11:47 PM
9. ### Finding the mean value when there is a trend in the dataset

I have a large data set. I want to get a representative value for this data set. So I calculated mean value for the data set. But there is a trend in...

• Replies: 2
• Views: 1,003
05-12-2015, 11:37 PM
10. ### Comparing percentages - Which test is the most suitable?

Hi Following advice received from an earlier posting, I have simplified the data I am analysing, and would like to check that I have made the...

• Replies: 3
• Views: 1,611
05-12-2015, 01:35 PM
11. ### Randomized Complete Block Design (question about my design)

Hello all- this is my first post on this lovely looking forum. This may be an advanced question! I would very much be grateful for any help. I...

• Replies: 5
• Views: 2,159
05-12-2015, 12:19 PM
12. ### Comparing variability of several independetly time series

To compare several independently distributed time series, I decided to take a compare their coefficient of variations. Is there any better way to...

• Replies: 0
• Views: 973
05-12-2015, 09:56 AM
13. ### Time Series

I have a data set of daily prices of some product. But for some days there are more than one price per day. Then is this a time series or not?

• Replies: 0
• Views: 877
05-12-2015, 12:03 AM
14. ### Directed acyclic graph

Hello I'm a beginner at epidemiology and have an assignment where I'm trying to create a DAG using dagitty to determine what to adjust for when...

• Replies: 1
• Views: 1,070
05-11-2015, 04:27 PM
15. ### A parametric hypothesis testing problem!

Hello guys, So I have this problem I am trying to solve and it

• Replies: 1
• Views: 1,171
05-11-2015, 08:20 AM
16. ### Time Intervals in R

I want to get some value to be printed if some input date is in between some two dates. How can I do this in R? The algorithm is as follows. If(x...

• Replies: 2
• Views: 1,492
05-11-2015, 04:55 AM
17. ### Welch t-test?

Several years ago, with the help of some experts in statistics, I selected the Welch t-test for an experiment of mine. I'm now reviewing that...

• Replies: 10
• Views: 3,917
05-11-2015, 01:43 AM
18. ### ANOVA or Chi Square for Nominal Non Parametric Data

Dear TalkStat Forum members, I was hoping to get some advice over whether I am using the appropriate test for data that I have. The notes of 70...

• Replies: 2
• Views: 1,640
05-11-2015, 01:36 AM
19. ### unequal sampling effort - binomial generalized linear model - offset

How to take into account heterogeneity in sampling effort in a binomial glm (presence absence) ? Edit I want to link species presence with...

• Replies: 3
• Views: 1,846
05-10-2015, 11:50 PM
20. ### stepAIC - summary(binomial GLM) - insignificant variables

Why stepAIC gives a model with unsignificant variables in the summary(model) ? I would like to know what environmental variables allows to explain...

• Replies: 4
• Views: 2,173
05-10-2015, 11:41 PM
21. ### When to use which statistics? Is it correct like this?

I never had statistics in school and I'm not in college yet so I try to teach in to myself now. That's why everything I write now could be plain...

• Replies: 1
• Views: 999
05-10-2015, 03:43 PM

Dear all We have performed PCA on a dataset and have the following results: Eigenvalues: Factor 1: 2.68 Factor 2: 0.23 Factor 3: 0.08

• Replies: 0
• Views: 883
05-10-2015, 03:03 PM
23. ### Help Would anyone please show me how to do this exercise. Thanks a lot

Suppose we have a sample X1,....Xn from a distribution with a pdf f(x) = -θ^x log(θ), with 0 <θ <1. 1) Find a 1-dimensional sufficient statistic...

• Replies: 1
• Views: 1,246
05-08-2015, 12:42 PM
24. ### Testing difference between two surveys related to stocks (not means)

Hi I need to answer if there is a significant difference between a stock obtained from two surveys. I've researched and i only find info about means...

• Replies: 0
• Views: 925
05-08-2015, 09:44 AM
25. ### Dissertation test results. Help!!!

Hi Guys, I was just wondering if you could help me out with some statistics stuff as I'm having a little trouble with interpreting my dissertation...

• Replies: 0
• Views: 980
05-08-2015, 09:27 AM
26. ### Removing outliers - endless story?

I've been collecting some data for the first time, investigating differences between three groups of people and their numbers of hospital visits....

• Replies: 18
• Views: 3,458
05-08-2015, 08:24 AM
27. ### Basic averages question

I am trying to work out the total average from a set of 5 averages. See below: Class 1: Total number of weeks = 12 Total number of hours =...

• Replies: 2
• Views: 1,401
05-08-2015, 03:01 AM
28. ### Buffon's needle/ Monte Carlo simulations

Hi, I've recently took M.C estimation course and we learned to evaluate pi with Buffon's needle. The probability of the needle intersecting the...

• Replies: 0
• Views: 1,670
05-08-2015, 02:27 AM
29. ### Age-Period-Cohort Model

I am looking for feedback on the feasability of a model I am specifying. I have four cohorts of longitudinal data. Each cohort contains ten years...

• Replies: 0
• Views: 1,108
05-07-2015, 09:59 PM
30. ### T series stationarity

hay guys, i'm working on garch models, but a cant turn my returns stationary. how can i do it? i've tried whit log return (logxt - logxt-1) but...

• Replies: 0
• Views: 1,179
05-07-2015, 11:47 AM
31. ### Compatibility of different numerical evaluations (mean averages, SD rates)

Dear all, I would like to make the results from two surveys compatible: In the first survey, numerical values are elicited from native...

• Replies: 0
• Views: 1,238
05-07-2015, 09:28 AM
32. ### T distribution - basic question I think

Hello, Is it possible to use a t test to test whether an individual observation is from the same population as a (small) sample?

• Replies: 7
• Views: 1,364
05-07-2015, 09:04 AM
33. ### Comparing groups?

Hi, I got a homework that I really don't now how to deal with. It goes: An investigator wants to compare the life lengths of Brand A with those...

• Replies: 0
• Views: 1,492
05-07-2015, 03:18 AM
34. ### How can I find out, if subscales are independent?

I need to find out, if four subscales of a scale a independent from each other in my sample. A correlation with all four is a good start, so I did...

• Replies: 26
• Views: 8,069
05-06-2015, 10:44 AM
35. ### Calculating a one-way anova with just means, stdev, and sample sizes

Hi How can you determine the sum of squares total, sum of squares within and between, only knowing the mean, standard deviation and sample size...

• Replies: 1
• Views: 2,158
05-06-2015, 08:27 AM
36. ### preparing to get a job

hi all i am a statistical engineer with no job for a year know , in fact last year i faced many problems that affect my psychology(overwork). I...

• Replies: 0
• Views: 1,232
05-06-2015, 03:45 AM
37. ### Finding confidence interval

I have a large data set of price (around 4000 data). By using this data set I want to find a representative value which represents the whole data...

• Replies: 4
• Views: 1,437
05-05-2015, 10:37 PM
38. ### Could someone verify my logic for managing probability distributions in an experiment

I'm not well versed in stats lingo, but am hoping my logic in the concepts here makes sense and is correct. Often in my work (measuring electrical...

• Replies: 0
• Views: 1,287
05-05-2015, 01:16 PM
39. ### t-test interpretation

Hi All, Can you please help me how to interpret the result of my t-test t-Test: Two-Sample Assuming Equal Variances Method...

• Replies: 7
• Views: 2,162
05-05-2015, 11:38 AM
40. ### Standardised Scoring

I have a dataset, which produces scores on a test. The best scores are those which are closest to zero, and then as scores get bigger this is worse....

• Replies: 1
• Views: 962
05-05-2015, 10:55 AM
41. ### Hypothesis Testing Help

Hello fellow statisticians! it's been awhile since I've done stats and everything has completely escaped me. I'm trying to conduct hypothesis...

• Replies: 0
• Views: 609
05-05-2015, 09:22 AM
42. ### Comparison of Groups geochem data-How to go about showing the statisical significance

Hi everyone, I just stumbled across your site; I am learning statistics by myself for my thesis (Bear with me please and sorry if I posted this in...

• Replies: 0
• Views: 1,159
05-05-2015, 08:20 AM
43. ### Solutions to problems in Mathematical statistics with applications, Wackerly.

Hey everyone. Can someone help me find solutions for the problems in the book mentioned in the titte? I am specielly interested in solutions to...

• Replies: 1
• Views: 2,999
05-05-2015, 06:03 AM
44. ### How to prepare for an exam that's in a month?

Hi, I have an exam coming up soon for university (http://handbook.uws.edu.au/hbook/unit.aspx?unit=300700.5) for the unit "Statistical Decision...

• Replies: 0
• Views: 1,138
Fox
05-05-2015, 01:24 AM
45. ### Understanding Heteroskedasticity

For the following statements I need to state whether they are true or false with brief reasoning: a) “If heteroskedasticity is present, the...

• Replies: 0
• Views: 1,414
05-04-2015, 11:16 PM
46. ### Confidence Interval homework help

This is the only part of our homework I am not understanding... A.)If the 95% confidence interval for the population mean is (6,20), what is the...

• Replies: 4
• Views: 1,549
05-04-2015, 04:47 PM
47. ### Geometric Distribution Problem.

Hi everyone! This is my first post here. I am currently a little stuck on a university workshop question. I was hoping to see my tutor during her...

• Replies: 2
• Views: 1,609
05-04-2015, 01:22 PM
48. ### Making sense of the parameter delta in this equation.

Hello, I was reading this paper about pollen dispersal directionality and I am trying to make sense of the so-called directionality parameter...

• Replies: 1
• Views: 1,389
05-04-2015, 10:35 AM
49. ### Dealing with missing value in dataset

My dataset contains matrix of 1k x 1k and each points having value ranging from 1 to 100. if value is 1, means that point value is lost. To...

• Replies: 0
• Views: 774
05-04-2015, 10:34 AM
50. ### Mixed ANOVA with covariate - interpretation help!!!

Hi, I conducted the following mixed ANOVA with a covariate: 2 x groups (BS factor) 3 x Switching as repeated measures (WS factor) IQ as...

• Replies: 3
• Views: 2,650
05-04-2015, 07:27 AM
51. ### Negative confidence intervals in regression

Hi all, So I'm really stumped. Basically I have a negative standardised coefficient value of -0.35, and a 95% CI equals (-0.47, -0.23). I'm having...

• Replies: 12
• Views: 3,879
05-03-2015, 10:20 PM
52. ### Assistance with ANOVA test

Hi everyone, I am analyzing data from 5 winogradsky columns and am looking at how sulfate concentrations change for 5 different depth categories:...

• Replies: 0
• Views: 945
05-03-2015, 07:30 PM
53. ### Result for study falls outside sample size margin of error?

Hi all, I was wondering it means for your results if they fall outside the margin of error used when calculating a sample size? Say I expected a...

• Replies: 0
• Views: 458
05-03-2015, 01:51 PM
54. ### Interpreting 2x4 repeated measures ANOVA

Hello, I am having some trouble interpreting the results of a 2x4 repeated measures ANOVA. Participants in my study ran through 4 music...

• Replies: 1
• Views: 1,209
05-02-2015, 08:27 AM
55. ### How to calculate binomial z-scores?

Hi, Basically I am trying to calculate binomial z-scores to determine individual significance of left or right. For example say there is a person...

• Replies: 0
• Views: 1,044
05-02-2015, 06:56 AM

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