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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: 197,146
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: 66,940
09-30-2005, 09:44 AM
1. ### Conditional probability question ~ why is P(H) = P(HH)+P(HT)?

Hi, I am told that the probability of an unfair coin is the following: P(HH) = 4/9 P(HT) = 1/9 I need to find what the probability of...

• Replies: 2
• Views: 1,382
10-18-2012, 03:54 AM
2. ### experiment: estimating candies in a jar

this is an experiment project for my class. there is a big jar filled with 2 types of candies. we need to estimate 3 things: A. how many Type A...

• Replies: 0
• Views: 1,464
10-16-2012, 08:39 PM
3. ### Comparison of ordinal data - same subjects, same questions, 5 years later

Hi all, I'm looking for a good way to represent changes in ordinal-type data. I have 2 sets of data. In the first set, 50 companies (which...

• Replies: 0
• Views: 1,737
10-16-2012, 03:23 PM
4. ### Two-Way ANOVA question

Hey guys I'm new to this form. I've had trouble with stats over the past three years. I'm fourth year university and only need this one statistics...

• Replies: 0
• Views: 3,593
10-16-2012, 03:00 PM
5. ### Compare Treatment Effects of 2 Groups - Repeated Measures & Binary Outcome

Hi, I have two groups (1:non-comorbid group, 2:comorbid group), where patients in one group have a condition that patients in the other group do...

• Replies: 0
• Views: 2,748
10-16-2012, 01:50 PM
6. ### Using regressions in monte carlo simulations

Hey Guys, I'm building a valuation model with monte carlo and regression elements but could use a bit of help. The model breaks down the...

• Replies: 0
• Views: 1,256
10-16-2012, 09:39 AM
7. ### Simulation of unlikely events over random binary variables knowing their probability

Hi, I have n binary variables all having the same probability p of flipping. Probability is low, so I wouldn't want to go through generating a...

• Replies: 3
• Views: 2,235
BGM
10-16-2012, 03:27 AM

Hi, I am in 6th grade, trying to do an analysis of data for a science fair project. Sorry, but I am only at Algebra 1, I do not have any...

• Replies: 12
• Views: 3,064
10-15-2012, 06:50 PM
9. ### A bit confused on confidence intervals

Why does the t-value for the 98% confidence interval increase to 2.33 from 1.96? Basically what determines these values and what does it mean?

• Replies: 3
• Views: 1,776
10-15-2012, 03:19 PM
10. ### How can i determine which predicted value is more accurate?

Hey everyone, So i did a simple linear regression on the data below: Assigned questions: (c) Predict the heart disease mortality...

• Replies: 4
• Views: 2,762
10-15-2012, 02:33 AM
11. ### Quick Q

How would I calculate a sample mean if I'm given the standard deviation and sample size? The example in the book says "The volume of liquid in a...

• Replies: 1
• Views: 1,241
BGM
10-14-2012, 11:31 PM
12. ### [SOLVED] Does n Affect Effect Size

We all know the pvalues are affected by sample size. I've had profs claim that effect size is unaffected by sample size. But I'm thinking this may...

• Replies: 6
• Views: 3,072
10-14-2012, 06:30 PM
13. ### Chow test. Testing difference between two years.

Hi Go down to the bottom "interpret results" if you want to skip right to my question :) I have been struggeling with my home assignment this...

• Replies: 3
• Views: 2,460
10-14-2012, 10:31 AM
14. ### Confidence interval & Hypothesis questions- Basic stats-

Hi all, I had a question I was working on and needed a review on the approach I was taking & figure out if the answer I have gotten is correct: ...

• Replies: 0
• Views: 1,820
10-13-2012, 10:03 PM
15. ### Analysing the effect of dilution on honey

Hello! I've currently got some data but I'm just become horribly stuck D: The data shows the inhibitory effect of varying dilutions of honey on...

• Replies: 6
• Views: 3,351
10-13-2012, 07:01 PM
16. ### Compute joint pdf

Random variable X1 is the number which corresponds to the point from the interval (0,1). Then choose a point at random from the interval (0,x1),...

• Replies: 1
• Views: 1,236
BGM
10-13-2012, 04:39 PM
17. ### Finding Cumulative Distribution Function

The probability density function of the time to failure of an electronic component in a copier (in hours) is f(x)=(e(-x/1000))/(1000). Need to...

• Replies: 1
• Views: 4,379
10-13-2012, 11:48 AM
18. ### Teaching Stats Text

Hi, I teaching a statistics course in the spring for the first time with the following description and wondered if anyone had a suggestion for a good...

• Replies: 4
• Views: 1,994
10-12-2012, 11:37 PM
19. ### Time series analysis ?!?!? Help :) !

I have collected time series data (100 or so data points in time sequence). They data sets look like they show cyclical trends however, I need to...

• Replies: 4
• Views: 1,674
10-12-2012, 05:35 AM
20. ### Randomized experiment analysis - DID, regression, help

Hi all, This is a basic question that may have been previously addressed, but I couldn't find it by searching and I'm very out of shape with my...

• Replies: 1
• Views: 980
10-11-2012, 01:38 PM
21. ### Cluster analysis basics

Hello, I've tried reading up on cluster analysis and have no completely confused myself after reading far too much sas code and far too many...

• Replies: 3
• Views: 1,683
10-11-2012, 03:09 AM
22. ### Confidence Interval of a Population

I am supposed to be finding the confidence interval for P(X=1) = EX = unemployment rate. I have X = 1 if unemployed, 0 if employed. Y = 1 if no...

• Replies: 0
• Views: 1,268
10-10-2012, 08:37 PM
23. ### Hit a brick wall

I have data that is clearly nonlinear. The data follows a line until a certain critical point at which increasing one variable causes the data to...

• Replies: 2
• Views: 1,493
10-10-2012, 08:00 PM
24. ### Sample or population

You have either a sample or population. But you know that N = 25 and you calculated the sample SD and got 5. You changed you mind and calculated the...

• Replies: 2
• Views: 1,335
nyo
10-10-2012, 07:01 PM
25. ### stats help pretty please :)

Hey guys, sooo i'm taking a stats class at my college because it is required for my major. I'm having a lot of trouble with the class especially with...

• Replies: 1
• Views: 1,367
10-10-2012, 06:34 PM
26. ### Challenging problem comparing categories (Wilcoxon?)

Hi all, I have kind of a tricky problem:confused: ... hope someone can help me! Suppose a couple of ethologists checked the probability...

• Replies: 0
• Views: 1,234
10-10-2012, 04:35 PM
27. ### Coin Toss "Guessing" Probability

Hi all, I have a quick question about a stats class assignment. We did the classic coin toss experiement. We tossed 10 coins 60 times. The first...

• Replies: 3
• Views: 3,366
10-10-2012, 04:03 PM
28. ### effect size to report or not

I challenged a prof today and I said that an effect size should not be reported for non significant results. He strongly disagreed. What are your...

• Replies: 18
• Views: 17,719
10-10-2012, 03:15 PM
29. ### One-group, pretest-posttest with aggregated count data (retention rate)

Hi, I'm doing an analysis where I would like to see if a group of people's behavior changes after being exposed to X. I know the proportion of...

• Replies: 1
• Views: 2,045
10-10-2012, 01:01 PM
30. ### Computer Science student need help: determine which formula is more accurate?

Hi guys, I'm an computer science student working on a project to build an app that can predict the Survival rate of a person. I have very little...

• Replies: 6
• Views: 1,658
10-10-2012, 10:46 AM
31. ### Testing Difference of Values from Lognormal Distribution?

I have data that fits a lognormal distribution really well. My primary goal is to create a statistical classifier using this distribution to apply to...

• Replies: 1
• Views: 1,365
10-10-2012, 08:02 AM
32. ### Chi-square, expected counts & Fischer exact test

Sitting here with a stat book and some questions are popping up. Chi-square assumes that expected counts are greater than 5. However, in larger...

• Replies: 1
• Views: 4,283
10-10-2012, 05:55 AM
33. ### Post hoc test for Fisher's excat test

Hi, :wave: I have a 3 x 3 contingency table with some cells < 5. Therefore I performed a Fisher's exact test. The result showed that there is at...

• Replies: 0
• Views: 2,474
10-10-2012, 05:31 AM
34. ### T tests

Intervention program of 10 weeks for women with depression and a three year folllow up. study has intervention group and control group - was...

• Replies: 0
• Views: 1,318
nyo
10-09-2012, 10:38 PM
35. ### How can I run survey for Proc Genmod?

Hello, I know that Proc Freq and Proc Means have options for survey sampling data by running Proc Survey Freq and Proc Survey Means. In Proc...

• Replies: 0
• Views: 2,974
10-09-2012, 09:50 PM
36. ### Odds & Risk Ratio

Hi, Just wondering if In a Prospective Case-Control 'risk factor' analysis with a relatively rare outcome of interest (6.7%). Does the Odds Ratio...

• Replies: 2
• Views: 1,996
10-09-2012, 08:27 PM
37. ### sdf

Sorry about the title, my young one got to the keyboard a little quicker than I could. I have data that I can use to indicate what percentage of...

• Replies: 1
• Views: 1,498
10-09-2012, 04:37 PM
38. ### Calculating Standard Deviation from percentage of whole

I am trying to calculate the standard deviation of this data. However, the data is presented in the format of under 100 lbs 2% under 110 lbs 4%...

• Replies: 0
• Views: 2,063
10-09-2012, 02:45 PM
39. ### statistical significance of conversions greater than 100%

Hi there, I am running a landing page test on Google AdWords for my retail website. The control is the current landing page where products are...

• Replies: 1
• Views: 1,150
10-09-2012, 01:44 PM
40. ### Who's a Gambler?

This is a fun one. The P(A) = 3/5. Find the "odds" of winning an A.

• Replies: 5
• Views: 1,781
10-09-2012, 12:04 PM
41. ### First Time Trying To Build A Forecasting Model Using Regression. Need Help Badly!

Hi Everybody, I have a project at work that I’m working on, and I seriously need some direction. I’m not a math or stats person, so this is all...

• Replies: 0
• Views: 1,001
10-09-2012, 09:31 AM
42. ### Trimming in Propensity score matching

Hi, Can some one please help me with how trimming is done in propensity score matching? what is the acceptable common trim percentage? Is low or...

• Replies: 0
• Views: 3,709
10-09-2012, 05:39 AM
43. ### (> one hour invested)

I have spent more time than I should this one. Given that P(A or B) = 1/4, P(A) = 1/7, and P(A and B) = 1/9, find P(B). I've worked it many...

• Replies: 1
• Views: 1,380
BGM
10-09-2012, 04:16 AM
44. ### Difference between sample and population

Now, in this case, will the given data for each group considered as sample or population ? I want to calculate SD, MD and Variance and i am...

• Replies: 1
• Views: 1,765
10-09-2012, 03:52 AM
45. ### Trend analysis

4 groups -6 points in each I calculated trend analysis and linear and cubic were significant How would do additional analysis that tests a...

• Replies: 3
• Views: 1,640
10-09-2012, 02:29 AM
46. ### Some questions I'm struggling with

Some help with these questions would be much appreciated A. The average price for a new car is \$18,000 and the standard deviation is \$1,500....

• Replies: 1
• Views: 3,194
10-08-2012, 06:09 PM
47. ### How to test for differences in quadratic means/variances?

Hello I have two groups of patients that underwent different surgical procedures. I would like to compare the groups to find differences between...

• Replies: 5
• Views: 2,032
10-08-2012, 02:27 PM
48. ### Correct Analysis Method for 1:1 and 1:4 Matched Studies with Continuous Outcomes?

I have several questions about analyzing 1:1 and 1:M matched studies that have a continuous outcome variables. 1.To determine difference in 2...

• Replies: 4
• Views: 7,758
10-08-2012, 02:13 PM
49. ### multivariate analysis?

Hi, I used mann whitney to see if any significance was shown between smokers (1) and non smokers (2), i found a p value for lung cancer 0.000 and...

• Replies: 1
• Views: 1,750
10-08-2012, 10:26 AM
50. ### Which test is best?

Hi, I have 511 patients where i have measured size of a bone (cancer patients), the mean is 0,31 cm then i have measured size of the same bone of...

• Replies: 4
• Views: 1,224
10-08-2012, 09:58 AM
51. ### Non-parametric post-hoc tests

In my biostatistics reference books, as well as what I have found on the web, there appears to be no easy way (at least as it pertains to software...

• Replies: 0
• Views: 947
10-08-2012, 09:57 AM
52. ### LSE of y = ax + bsinx

Hello, How may a LSE of a and b be determined if y = ax + bsinx?

• Replies: 1
• Views: 1,145
10-08-2012, 12:37 AM
53. ### Help writing what I'm doing mathematically

I am not a mathematician and thus need major help representing my actions mathematically. First I'll explain what I'm doing and then a crack at...

• Replies: 13
• Views: 2,646
10-07-2012, 10:25 PM
54. ### Error on half life.

Hello, I have five Geiger counter readings taken at five short (1 minute) hourly intervals. If I plot lnR against count rate to find the decay...

• Replies: 0
• Views: 1,488
10-07-2012, 08:18 PM

Hello, We have been working on an assignment of t-test analysis, but the data we got look very puzzling and perplexing. I really need your help! ...

• Replies: 0
• Views: 1,092
10-07-2012, 08:03 PM
56. ### Anova and SD

(provided anova summary table) The design has equal n, 4 groups that have same Standard deviation of 3.45 woudnt a fifth group have the same SD?

• Replies: 0
• Views: 1,047
nyo
10-07-2012, 03:34 PM
57. ### standard error and sampling distribution?

I totally and completely lost in my statistics class. We're learning about z-scores, probability, and testing hypothesis. I have two homework...

• Replies: 4
• Views: 4,431
10-06-2012, 11:20 PM

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