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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: 196,665
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: 66,688
09-30-2005, 09:44 AM
1. ### Temperature vs Concrete Cure Time

Hello, I have a reasonable sized data set of concrete cure times and the average temperature when the pour was done. What I am trying to do is...

• Replies: 2
• Views: 6,031
11-12-2012, 03:45 PM
2. ### non-parametric tests and post-hoc analysis

Hi. I have the following problem: I have a set of data coming from 5 different ventilators, tested in a bench study. Different variables (insp...

• Replies: 0
• Views: 1,760
11-12-2012, 01:44 PM
3. ### Comparing compression strength of chocolates

Hey there, Im currently working on a project to compare the compression strength of chocolates with different inside filling (caramel, nuts,...

• Replies: 4
• Views: 1,998
11-12-2012, 09:33 AM
4. ### (Binominal proportions) confidence interval  which formula to use?

Hey, I got a quick question regarding confidence intervals. For a Rasch analysis I have to perform independent t-tests (its done to check for...

• Replies: 2
• Views: 26,860
11-12-2012, 06:30 AM
5. ### Confidence Intervals

• Replies: 1
• Views: 1,578
11-11-2012, 09:42 PM
6. ### Anova or mixed model, and is non-orthogonality a problem?

Hello, I am trying to test whether the following variables affect likelihood of visits by squirrels to feeding stations: Distance of feeder...

• Replies: 8
• Views: 2,166
11-11-2012, 05:31 PM
7. ### Question about EV sum SE sum.

1. The average weight of people is known to closely follow a normal curve. Suppose the average weight of 3,000 people is 150 lbs, with an SD of 10...

• Replies: 0
• Views: 2,544
11-11-2012, 04:31 PM
8. ### creating a composite variable?

I am a student doing my master's thesis and I have a question regarding my study. I am working with country data for 25 countries and I am looking...

• Replies: 0
• Views: 2,500
11-11-2012, 11:30 AM
9. ### Using a large constant value for a log transformation of data with zeros

I have a rather large data set, positively skewed. I'm using a log transformation, but there are quite a few zeros in my data since the data is time...

• Replies: 3
• Views: 2,421
11-11-2012, 10:23 AM
10. ### How derive joint distribution of x1, x2, x3, sum(xi) following poisson disribution?

At first, i try to solve the problem, "Let X1, X2, ,,, Xn be a random sample from a Poisson distribution with mean theta. find the conditional...

• Replies: 1
• Views: 4,688
BGM
11-11-2012, 06:47 AM
11. ### Different correlation coefficients

How can i compare the results determined by different correlation coefficients between different type of variables? Two of the three variables are...

• Replies: 0
• Views: 1,489
11-11-2012, 05:17 AM
12. ### Multiple Comparison Procedure hw- which is best?

If there are 4 independent groups of 7 subjects each, which multiple comparison procedure is best to achieve maximum power while maintaining...

• Replies: 0
• Views: 1,112
11-11-2012, 02:21 AM
13. ### Lin Regression: Need help predicting y from R and x= mean + 1.5 standard deviation

Hi, I have the following linear regression problem "For r = .60 and a x that is 1.5 standard deviations above the mean x, I expect a dependent...

• Replies: 1
• Views: 916
11-10-2012, 04:08 PM
14. ### multivariate regression in stata

Hello, can i use xtfmb.ado in stata to make famamacbeth regression where i regress dependent variable on multiple independent variables? if so,...

• Replies: 0
• Views: 1,649
11-10-2012, 03:05 PM
15. ### Using Minitab to test Null hypothesis of two population variance

Hey guys, 3 weeks ago I came across a problem that stumped me for my statistics course I'm enrolled in, and you were all so helpful I had to come...

• Replies: 2
• Views: 1,767
11-09-2012, 03:21 PM
16. ### expectation between two variables

Hey guys, Stuck on a question and hoped someone could see it easier than I am currently. I was asked to caculated an expectation (as part of a...

• Replies: 5
• Views: 1,125
11-09-2012, 12:57 AM
17. ### Binomial Distributions?

suppose you purchase a bundle of 10 bare-root broccoli plants the sales clerk tells you that on average you can expect 5% of the plants to die before...

• Replies: 1
• Views: 1,772
11-08-2012, 07:19 PM
18. ### MGF question

Not to familiar with Moment Generating Functions will some one walk me though this example.... MGF of X1+X2+X3+X4 and MGF or X3+X4

• Replies: 1
• Views: 1,188
11-08-2012, 02:41 PM
19. ### Combining Variance of different groups

Hello I am a new member here and I have got a query on combining variances of two or more sets of groups. Say there are m+n elements split into two...

• Replies: 0
• Views: 2,253
11-08-2012, 11:55 AM
20. ### calculating the absolute error between two transition tables, simple but confusing :)

Dear all , I have a simple yet confusing problem, I am trying to figure out which is the correct approach to proceed. Here it goes I have a...

• Replies: 2
• Views: 1,296
11-08-2012, 09:10 AM
21. ### 4 times the same experiment with 4 conditions in each experiment: 2-way ANOVA?

I have run 4 times the same experiment and in each experiment I have the same 4 conditions. In each group, in each experiment, I have 3 to 5 mice. I...

• Replies: 2
• Views: 1,318
11-08-2012, 06:21 AM
22. ### Simple test needed

Hi all I have some a polygon area that is an output from an environmental model and some discreet data points some of which fall withing the...

• Replies: 2
• Views: 1,173
11-08-2012, 05:21 AM
23. ### which test to use

Hey, I do have data on the nutritional status children as well as the education level of the father - it is a table with four educational levels...

• Replies: 2
• Views: 1,435
11-08-2012, 05:06 AM
24. ### Derivative of Geometric Progression [WITHOUT] Differentiation?

Dear friends, I am trying to find the Var(X) of a Shifted Geometric Progression to solve a question that I have to present in class. I referred...

• Replies: 3
• Views: 1,862
BGM
11-08-2012, 04:45 AM
25. ### Can someone help me with a statistics question regarding a T Score (capital 'T')

I am studying to take the GRE-Psychology subject exam and there is a stats question in the Educational Testing Services practice exam book that I...

• Replies: 2
• Views: 3,761
11-07-2012, 08:43 PM
26. ### Why would an attribute in a data set not be included in a generated decision tree?

Say I have a data set of customers with information such as bank account, age, telephone, credit history, emplyoment, etc... How could when I used...

• Replies: 0
• Views: 1,182
11-07-2012, 04:00 PM
27. ### Combining Sample Statistics for Higher Precision, possible? Under what conditions?

Say I have dozens of samples and with them dozens of estimates of a population's mean along with associated confidence intervals -the samples could...

• Replies: 6
• Views: 2,345
11-07-2012, 03:37 PM
28. ### what is the similarity between Karl pearson cross product and Gauss discovery

Gauss’s childhood insight into how to sum large sets of numbers in a linear series is analogous to that underlying the cross-products formulation for...

• Replies: 3
• Views: 2,257
11-07-2012, 02:24 PM
29. ### Spear man Rank-order question

In ranking the quality of the last six red wines tasted, you and your signiﬁcant other (a.k.a. spousal unit) agree, except inexplicably on the...

• Replies: 4
• Views: 1,630
11-07-2012, 02:21 PM
30. ### Did I deisgn this wrong? Using dummy variables for Y

Hi all, Thanks for taking a look at this. Regression Statistics Multiple R 0.908734206 R Square 0.825797856 Adjusted R Square...

• Replies: 3
• Views: 1,628
11-07-2012, 12:04 PM
31. ### Home work help

Hi! I am in need for advice on this, for me at least as new to the subject (have only taken 15 ECTS), tricky question: Anyone who could help...

• Replies: 1
• Views: 858
11-07-2012, 11:25 AM
32. ### need help finding p-value for presentation

here is the question i will have to present in class In a process of manufacturing metal piece using two different cooling processes. In order to...

• Replies: 1
• Views: 897
11-07-2012, 11:01 AM
33. ### No significance in ANOVA, significance in t-test. Am I doing this wrong?

Hi folks. I've got a set of chemical measurements taken from three different groups -- a control soil, a low-contamination soil, and a high...

• Replies: 3
• Views: 1,459
11-07-2012, 06:01 AM
34. ### Test median again hypothesized median value_ one sample Wilcoxon signed ranks test

I have a question regarding testing a median against a hypothesized value. On a five-point Likert-style scale (1=regressed; 5 = met goal ),...

• Replies: 6
• Views: 4,829
11-07-2012, 05:32 AM
35. ### Moe, Hannah, and Mathguy chatting it up

Mittens suﬀers from Romnesia an average of 5 times per week. However, Joe Im just sayin Biden claims that Mittens rarely suﬀers from fewer than...

• Replies: 15
• Views: 2,865
11-07-2012, 01:17 AM
36. ### Probability John wins the game (X) given...

I am so stumped. What is the probability John wins the game, given: Coming into the game, John should win 90% of the time, BUT an average...

• Replies: 4
• Views: 1,643
11-06-2012, 06:01 PM
37. ### Significance testing on share of spend

Hi all, can someone point me in the right direction for how i would work out stat sig of share of spend? eg - 5 companies in market, ask ppl...

• Replies: 1
• Views: 2,537
11-06-2012, 05:35 PM
38. ### ACF plot in Non Stationary Time Sereis

Hello Folks I know that in non-stationary time series, the Auto Correlation Function plot dies down extremely slowly while if the series is...

• Replies: 0
• Views: 3,921
11-06-2012, 05:21 PM
39. ### Study Design Question

I have a study design question for you. I'm designing a study that will implement a bully prevention program into schools. The study will consist of...

• Replies: 18
• Views: 3,022
11-06-2012, 03:29 PM
40. ### Statistical test for consistent performers!

Hi All, I have the data of firm performance (say on a scale of 10) for 50 firms over 10 years. Which statistical test (with significance levels)...

• Replies: 3
• Views: 1,839
11-06-2012, 12:11 PM
41. ### Confidence interval and proportions

Can someone see if this is correct? To devise effective marketing strategies it is helpful to know the characteristics of your customers. A study...

• Replies: 3
• Views: 1,268
11-06-2012, 06:53 AM
42. ### Sst= ssw+ssb

Hi everyone, I have this problem to solve. It's been a while since I tried to figured out how to do, but I am totally lost. Here it is. Prove...

• Replies: 0
• Views: 4,087
11-05-2012, 11:31 PM
43. ### Hypothesis tests applied to two means (two related samples) question about null.

Hello, I am currently studying for an midterm, and am running into a roadblock with some of the concepts concerning hypothesis testing applied to...

• Replies: 0
• Views: 1,508
11-05-2012, 09:05 PM
44. ### Building Fuel tables from scratch... Well with lots and lots of data!

Hey guys, I was hoping someone can push me in the right direction. I'm not asking for you guys to do my work but rather just point me in the right...

• Replies: 0
• Views: 598
11-05-2012, 07:51 PM
45. ### Conditional Multivariate Probability

So, I got this from my textbook and it makes sense: P_{Y|x}(y)= P(Y=y|X=x) = P_{X,Y}(x, y)/P_X(x) But I'm trying to apply it to this question...

• Replies: 8
• Views: 3,400
11-05-2012, 07:33 PM
46. ### Determining which statistical test to use and how to figure out sample size

Hello, I'm looking to collect data for the organization that I work for (a senior retirement community management company) and draw correlations...

• Replies: 0
• Views: 3,127
11-05-2012, 05:32 PM

Hi! I am wondering what kind of datatype our new variable will get if we add variables that have ordinal datatype. For example: SWLS scale that...

• Replies: 1
• Views: 1,241
11-05-2012, 02:06 PM
48. ### Control for yearly effects

Hi everybody, of course, I tried to find a thread with an answer about my topic. Unfortunately without success. I ran a multi regression...

• Replies: 2
• Views: 987
11-05-2012, 11:27 AM
49. ### Correlation question ( how long you live and your height)

In a recent study, among the very elderly (85+ years) of the sample, few (only 5.5%) of the men were over 1.9 metres tall. Yet, among their...

• Replies: 0
• Views: 1,079
11-05-2012, 01:35 AM
50. ### Confused about paired vs. independent samples for t-tests

I have viewed numerous websites and statistics resources and all state that paired samples are used for before and after comparisons in the same...

• Replies: 2
• Views: 1,669
11-05-2012, 12:03 AM
51. ### A particular type of random coefficient regression

Hi all, I have the model of type Y_i=Beta_0_i+Beta_1_i*X1_i+...+Beta_k_i*X_k_i, for i=1:n There is no error term in this model, but for each...

• Replies: 0
• Views: 1,037
11-04-2012, 11:40 PM
52. ### Need some help with basic Statistics

I've got a small table, as follows: GROUP n xbar (s/rootn) Alcohol: 25 0.25 0.05 Placebo: 25 0.12 0.03 It asks me for...

• Replies: 0
• Views: 2,415
11-04-2012, 10:24 PM
53. ### Confused with two-way ANOVA hypotheses

Hello all, I am working on my assignment of two-way ANOVA and feel totally lost. In my understanding, hypotheses for two-way ANOVA are three. ...

• Replies: 0
• Views: 1,130
11-04-2012, 06:31 PM
54. ### Missing values - too many?

Hi, Currently I'm doing research on analyst forecast accuracy and want to add another variable to my research: number of industries followed by an...

• Replies: 6
• Views: 2,792
11-04-2012, 07:21 AM
55. ### Standard deviation problems

1. Suppose the lifetime of a certain types of televisions follow an exponential distribution with a median of 7 years. Assume the warranty period is...

• Replies: 1
• Views: 1,402
11-03-2012, 02:43 PM
56. ### how to prove SSE has n-2 degrees of freedom???

make use of matrix or?

• Replies: 4
• Views: 3,881
11-03-2012, 12:01 PM

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