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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: 196,682
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: 66,707
09-30-2005, 09:44 AM
1. ### I need to solve step by step these statistic problems

I need to solve step by step these statistic problems, please do not use software, statistic tables are ok

• Replies: 19
• Views: 4,384
12-01-2014, 06:56 PM
2. ### Sampling: Stratified with proportional allocation vs. Simple Random Sampling

Hello, My question is about a proof in Lohr's Sampling: Design and Analysis. I have no clue what happened in the last step(which I outlined in the...

• Replies: 0
• Views: 1,018
12-01-2014, 05:16 PM
3. ### Completely lost in HW

I have some questions that I need help with. I have a few hours today, if there is anyone out there who could help me. I would truly appreciate it....

• Replies: 5
• Views: 1,677
12-01-2014, 10:32 AM
4. ### Homework help, want to check my method for probability and hypothesis test

I would be most obliged if someone would look at my solution and advise if my method and answers are correct. Mean lifetime of brand X bulbs is...

• Replies: 0
• Views: 1,898
12-01-2014, 08:12 AM
5. ### Repeated-Measures for men and women viewing opposite sex visual stimuli?

In advance, thank you for any insight you can provide on the following. My study: Men and women viewing different (opposite sex) stimuli (2...

• Replies: 6
• Views: 1,901
12-01-2014, 04:55 AM
6. ### Anybody give me idea about my solution?

My solution is n =30, = 0.795, s^2 =0.000586 99% confidence interval of σ = (0.018,0.036)

• Replies: 0
• Views: 1,416
12-01-2014, 12:50 AM
7. ### t test or wilcoxon signed rank test?

Hope you can help me. I am currently doing a masters research proposal (experiment hasn't been completed yet) and need to decide what statistical...

• Replies: 3
• Views: 1,553
11-30-2014, 08:33 PM
8. ### statistics help for fourth year biopharmaceutical science student

Hi I am just looking for advice on how to source some websites or books that may be of help to me with my statistics module. I currently have an...

• Replies: 0
• Views: 1,275
11-30-2014, 04:01 PM
9. ### linear or exponencial?

Hi all, I would like to find out, if there is any quantitative method for evaluation, if relationship between two variables is rather linear or...

• Replies: 1
• Views: 1,107
11-30-2014, 10:34 AM
10. ### Multiple Regression Multiple Choice Questions - Is this correct?

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• Replies: 3
• Views: 2,139
11-30-2014, 10:18 AM
11. ### Intervals for a grouped relative frequency distribution

What are the intervals of a grouped relative frequency distribution of a Z distribution? The range of the Z distribution is minus infinity to plus...

• Replies: 0
• Views: 1,288
11-30-2014, 09:22 AM
12. ### Pearson coefficient and dispersion

How do i know how much dispersion can i explain with Pearson coefficient? Thank you for the answers.

• Replies: 2
• Views: 1,665
11-30-2014, 03:45 AM
13. ### What design does my study have?

Say for example I wanted to do a study comparing cats (the control group) and dogs, measuring the extent to which they exhibit 4 behavioural...

• Replies: 2
• Views: 1,278
11-30-2014, 03:33 AM
14. ### Homework help - double-checking understanding

I've been going through some basic stats multi-choice past papers and there are a couple of questions I'm not 100% about. Would be grateful is...

• Replies: 0
• Views: 1,190
11-29-2014, 03:23 PM
15. ### How to determine if sample represents population

I hope this isn't a strange or a foolish question. I am wondering if there is anyway to demonstrate that a sample set represents the population when...

• Replies: 5
• Views: 2,529
11-29-2014, 06:55 AM
16. ### Probability question

Can someone help me with this question? A segment size is 18% of the sample. 88% of the segment will buy laptop in the next 6months, 7% of the...

• Replies: 1
• Views: 1,204
11-28-2014, 08:15 PM
17. ### Time series correlation versus average error

Hi there, I have two time series of pollution. I've computed the average error between the two device to be 7 ppb and the correlation...

• Replies: 0
• Views: 734
11-28-2014, 11:51 AM
18. ### which test(s) do I use?

Hi, This is not a homework question, it's to do with research. I have two groups of sequences of reals. As a pretend tiny example: group 1...

• Replies: 0
• Views: 1,339
11-28-2014, 02:15 AM
19. ### Net Promoter Score - Calculating Confidence Intervals and Margin of Error

Hello, In my sample of 1162, I have 291 Promoters, 476 Neutral and 395 Detractors. I therefore have an NPS of -9. We have calculated a...

• Replies: 3
• Views: 2,284
11-27-2014, 10:24 PM
20. ### Re: Selecting appropriate Stat Test and measurement

Problem Statement: Unclear as to which is the most suitable test to apply to the following data. (Also, is what is being outlined and proposed even...

• Replies: 2
• Views: 1,589
11-27-2014, 10:23 PM
21. ### Definition of z-score...

I need help with this question: Define the standardized value or z-score corresponding to a given observation y in a normal distribution. Explain...

• Replies: 4
• Views: 2,284
11-27-2014, 10:15 PM
22. ### Analyzing a Line Chart

I have a line chart with number of people on the y axis and weeks on the x axis. I was wondering if someone knew how to analyze or determine the...

• Replies: 2
• Views: 1,281
11-27-2014, 10:01 PM
23. ### ANOVA - basic assumptions

I'm trying to answer a question about the assumptions of ANOVA - my understanding (and checked on here:...

• Replies: 1
• Views: 1,106
11-27-2014, 04:17 PM
24. ### LInear discriminant analysis

I have been reading up on LDA and I found the following on Wikipedia Homogeneity of variance/covariance (homoscedasticity): Variances among...

• Replies: 0
• Views: 1,361
11-26-2014, 11:08 PM
25. ### Binary Logisitic regression to predict treatment type using time (year)?

Hello! I have some small data to work with, to look at whether one health centre has shifted from using treatment A to treatment B over time...

• Replies: 2
• Views: 1,518
11-26-2014, 10:40 PM
26. ### Signal detetion analysis d prime

Can anyone answer this please, I have no idea how to work out d' or response bias: In an experiment on the effect of alcohol consumption on...

• Replies: 2
• Views: 1,830
11-26-2014, 06:51 PM
27. ### what is the difference between formative models vs reflective models ?

Hello Can someone explain to me with easy example to make me understand the difference between formative and reflective models ?

• Replies: 1
• Views: 3,624
11-26-2014, 02:55 PM
28. ### Linear regression help?

How can I check if there is linear regression between the descent rate of flights at 1000 feet and 900 feet and so forth?? Should I look into...

• Replies: 2
• Views: 1,854
11-26-2014, 11:41 AM
29. ### Goodness-of-fits tests.

I honestly have no idea where to even start in this assignments. Any type of ell would be greatly appreciated. I can easily do the problems given in...

• Replies: 1
• Views: 1,700
11-26-2014, 12:21 AM
30. ### Can the game show Deal or No Deal be treated the same way as The Monty Hall Problem?

Hi guys, I'm quite new to this forum so I'm sure I put this question in the wrong section but oh well. Today in Physics, we got off topic and were...

• Replies: 3
• Views: 2,181
11-25-2014, 09:28 PM
31. ### Interpreting regression analysis low R-square AND low p value

Wanted to check my understanding of interpreting the results of a regression analysis with a large sample - a very low R-square (0.003) and low...

• Replies: 3
• Views: 2,447
11-25-2014, 12:37 PM
32. ### Measuring Team Performance. From a non-Statistician

Sorry. Some naive questions which might not make sense to statisticians but if anyone can give me some guidance on this. It's a situation I've...

• Replies: 3
• Views: 2,098
11-25-2014, 11:29 AM
33. ### Sign test, P-Values, Sign Ranked test.

Don't know how to delete post!

• Replies: 0
• Views: 1,166
11-25-2014, 11:22 AM
34. ### Measurement error bias questions?

• Replies: 1
• Views: 1,856
11-25-2014, 01:06 AM
35. ### How to test significance?

A reviewer on my (qualitative!) paper has suggested using some small-N statistical tests for my findings. I am a stats-idiot and would love a bit of...

• Replies: 5
• Views: 1,639
11-24-2014, 05:15 PM
36. ### Which analysis to choose

Hello 14 years after my graduation I study again in a masters program in which statistics is also a part. Now, doing some Progress I have a homework...

• Replies: 3
• Views: 1,340
11-24-2014, 04:06 PM
37. ### Confidence Interval for Sample and T-Test

For the sake of illustration, I am using a caliper mounted in stand A and measuring a part 20 times. This gives me a mean of 2mm and a 99% CI of...

• Replies: 7
• Views: 1,823
11-24-2014, 02:57 PM
38. ### How do you tease out how many people a study result applies to (x out of 100)?

I'm doing a large meta analysis of systemic causes to skin disease, and I'm trying to present people the following aggregates: Average effect...

• Replies: 0
• Views: 1,556
11-24-2014, 02:32 AM
39. ### Question about two-way anova with interaction effect

Hi! I just read this from a textbook on the topic of two-way anova: "If interaction effect between factor A and factor B is significant, we cannot...

• Replies: 4
• Views: 2,508
11-23-2014, 10:26 PM
40. ### Normally distributed mean values and the student's t-test.

Hi, These are potentially stupid questions, but bear with me – I am not a statistician nor a mathematician. If a group of observations is...

• Replies: 2
• Views: 1,515
11-23-2014, 03:18 PM
41. ### Logistic regression cutoff at 0.3

Hi, I have built a logistic regression model with misclassification rate around 18%. When I look at the ROC curve(area under the curve is 0.76)...

• Replies: 3
• Views: 1,373
11-23-2014, 07:12 AM
42. ### Inventory management from Donald Waters pg 75 .

I want to know how did he calculate the holding cost for EOQ model. Ques.:- Sarah Brown works for a manufacturer that makes parts for marine...

• Replies: 0
• Views: 1,112
11-23-2014, 05:21 AM
43. ### Credit Risk Transition Marix

Hi guys This is more of a finance/credit risk question but I wasn't sure where else I could ask this. Hopefully some of you may have heard the...

• Replies: 0
• Views: 2,016
11-23-2014, 12:05 AM

Hi everyone, I got a big problem with proving the lemma of checking independence for normal variable sample by merely checking the covariance, anyone...

• Replies: 0
• Views: 1,341
11-22-2014, 09:43 PM
45. ### Poisson Distribution - Time Interval

I think I worded this wrongly in my previous post...so I am posting again. I have a system that on AVERAGE it receives orders in a poisson...

• Replies: 1
• Views: 2,158
11-22-2014, 09:46 AM
46. ### possion dist.

Hello to all. I have a system that receives orders in a possion distribution with a mean of 2 per day. If I want to increase the orders by 12 per...

• Replies: 5
• Views: 1,839
11-22-2014, 09:03 AM
47. ### Interesting question involving gaussians

You are given two Gaussian variables: X_1 and X_2 with means m_1, m_2 and variance v_1, v_2. Suppose you know the sum X_1 + X_2 is equal to n....

• Replies: 1
• Views: 1,606
BGM
11-21-2014, 05:14 PM

I have three variables that I need to find the right probability distribution for 1) Aircraft Vertical Speed ( Descent rate) 2) Vertical Speed...

• Replies: 1
• Views: 1,295
11-21-2014, 11:06 AM
49. ### Which t-test (complication)?

Hi there, Im new here but any help would be greatly appreciated :) I have 48 lettuces which were judged by their weights (grown in separate pots)....

• Replies: 7
• Views: 1,990
11-20-2014, 11:32 AM
50. ### Reaching a 95% Confidence level within an estimated population.

I have a population of 367 products of which I have a sample of 50. Products can have a damaged package or can be damaged itself. We know for a fact...

• Replies: 0
• Views: 1,364
maq
11-20-2014, 02:50 AM
51. ### Need an idiot's guide on how to present findings from differing sample size, please.

I need to present my findings of survey ratings of 4 products that are based on differing numbers of people asked. Ie Product A 14...

• Replies: 1
• Views: 1,701
11-19-2014, 08:01 PM
52. ### How do I account for non-responders bias in a survey?

We survey leads after three months to determine the final outcome (became a sale, lost to a competing brand, lost to a competing technology, still...

• Replies: 2
• Views: 1,189
11-19-2014, 05:02 PM
53. ### What's the difference between model prediction and model validation?

Hello! I learned from a statistics course that there are two different regions regarding building regression models: one is for the purpose of...

• Replies: 1
• Views: 1,140
11-19-2014, 04:58 PM

I think I may be over my head just by being here, but I need help figuring out a real world problem. I have 49 different categories I want to...

• Replies: 3
• Views: 1,392
11-19-2014, 04:19 PM
55. ### A question about whether dropping interaction terms as a whole or not

Hello! I'm taking a regression course this semester and I have a question regarding when to drop the interaction terms. Suppose we have a...

• Replies: 3
• Views: 1,063
11-19-2014, 04:14 PM

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