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Forum: Statistics

Statistics course and homework discussion. Elementary statistics.

  1. Sticky Thread 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...

    Started by TheEcologist‎, 11-27-2010 12:13 PM
    • Replies: 1
    • Views: 197,146
    07-16-2014, 11:01 AM Go to last post
  2. Arrow Sticky Thread 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)...

    Started by quark‎, 09-30-2005 09:44 AM
    • Replies: 0
    • Views: 66,940
    09-30-2005, 09:44 AM Go to last post
  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...

    Started by gameomega‎, 10-18-2012 01:10 AM
    • Replies: 2
    • Views: 1,382
    10-18-2012, 03:54 AM Go to last post
  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...

    Started by iniesta13‎, 10-16-2012 08:39 PM
    • Replies: 0
    • Views: 1,464
    10-16-2012, 08:39 PM Go to last post
  3. Question 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...

    Started by ajvar‎, 10-16-2012 03:23 PM
    • Replies: 0
    • Views: 1,737
    10-16-2012, 03:23 PM Go to last post
  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...

    Started by mattpeters1‎, 10-16-2012 03:00 PM
    • Replies: 0
    • Views: 3,593
    10-16-2012, 03:00 PM Go to last post
  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...

    Started by okie1125‎, 10-16-2012 01:50 PM
    binary outcome, longitudinal, repeated measures
    • Replies: 0
    • Views: 2,748
    10-16-2012, 01:50 PM Go to last post
  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...

    Started by Bokononblue22‎, 10-16-2012 09:39 AM
    heteroscedasticity, monte carlo, regression coefficient
    • Replies: 0
    • Views: 1,256
    10-16-2012, 09:39 AM Go to last post
  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...

    Started by stanmoon‎, 10-16-2012 01:44 AM
    expectancy, random, simulation, variance
    • Replies: 3
    • Views: 2,235
    10-16-2012, 03:27 AM Go to last post
  8. Please Help - How Do I Prove Hypothesis?

    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...

    Started by Sci‎, 10-15-2012 10:40 AM
    anova, help please, null hypothesis, prove data
    • Replies: 12
    • Views: 3,064
    10-15-2012, 06:50 PM Go to last post
  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?

    Started by 1in10croak‎, 10-14-2012 10:06 PM
    • Replies: 3
    • Views: 1,776
    10-15-2012, 03:19 PM Go to last post
  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...

    Started by KingJames‎, 10-08-2012 09:39 PM
    • Replies: 4
    • Views: 2,762
    10-15-2012, 02:33 AM Go to last post
  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...

    Started by katcity‎, 10-14-2012 09:22 PM
    • Replies: 1
    • Views: 1,241
    10-14-2012, 11:31 PM Go to last post
  12. Calculating the residual?

    Hello, Based on the attached picture, I am supposed to calculate B1(hat) and B0(hat), which I have done successfully. B1(hat) = 0.451 and...

    Started by Walowizard‎, 10-14-2012 08:42 PM
    • Replies: 7
    • Views: 2,430
    10-14-2012, 10:26 PM Go to last post
  13. [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...

    Started by trinker‎, 10-14-2012 04:54 PM
    effect size
    • Replies: 6
    • Views: 3,072
    10-14-2012, 06:30 PM Go to last post
  14. 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...

    Started by slash‎, 10-14-2012 05:25 AM
    • Replies: 3
    • Views: 2,460
    10-14-2012, 10:31 AM Go to last post
  15. 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: ...

    Started by zkge‎, 10-13-2012 10:03 PM
    • Replies: 0
    • Views: 1,820
    10-13-2012, 10:03 PM Go to last post
  16. 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...

    Started by skimmx‎, 09-30-2012 11:54 AM
    • Replies: 6
    • Views: 3,351
    10-13-2012, 07:01 PM Go to last post
  17. Unhappy 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),...

    Started by Shirley‎, 10-13-2012 04:16 PM
    • Replies: 1
    • Views: 1,236
    10-13-2012, 04:39 PM Go to last post
  18. 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...

    Started by Stat_spec‎, 10-13-2012 10:28 AM
    • Replies: 1
    • Views: 4,379
    10-13-2012, 11:48 AM Go to last post
  19. 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...

    Started by gambs‎, 10-12-2012 02:43 PM
    • Replies: 4
    • Views: 1,994
    10-12-2012, 11:37 PM Go to last post
  20. Talking 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...

    Started by P.ENGOO‎, 10-11-2012 08:05 AM
    • Replies: 4
    • Views: 1,674
    10-12-2012, 05:35 AM Go to last post
  21. 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...

    Started by jas665‎, 10-11-2012 12:23 PM
    • Replies: 1
    • Views: 980
    10-11-2012, 01:38 PM Go to last post
  22. 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...

    Started by kwak123‎, 10-10-2012 07:31 AM
    • Replies: 3
    • Views: 1,683
    10-11-2012, 03:09 AM Go to last post
  23. 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...

    Started by wtrmlncrawl191‎, 10-10-2012 08:37 PM
    • Replies: 0
    • Views: 1,268
    10-10-2012, 08:37 PM Go to last post
  24. 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...

    Started by brandt‎, 10-10-2012 07:44 PM
    • Replies: 2
    • Views: 1,493
    10-10-2012, 08:00 PM Go to last post
  25. 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...

    Started by nyo‎, 10-10-2012 05:58 PM
    • Replies: 2
    • Views: 1,335
    10-10-2012, 07:01 PM Go to last post
  26. 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...

    Started by BrittneyUSCgirl<3‎, 10-10-2012 06:10 PM
    • Replies: 1
    • Views: 1,367
    10-10-2012, 06:34 PM Go to last post
  27. Question 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...

    Started by PonderingMath‎, 10-10-2012 04:35 PM
    • Replies: 0
    • Views: 1,234
    10-10-2012, 04:35 PM Go to last post
  28. 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...

    Started by jab1023‎, 10-10-2012 12:47 PM
    • Replies: 3
    • Views: 3,366
    10-10-2012, 04:03 PM Go to last post
  29. 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...

    Started by trinker‎, 10-09-2012 12:32 PM
    2 Pages
    1 2
    effect size
    • Replies: 18
    • Views: 17,719
    10-10-2012, 03:15 PM Go to last post
  30. 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...

    Started by ceperras‎, 10-10-2012 12:30 PM
    • Replies: 1
    • Views: 2,045
    10-10-2012, 01:01 PM Go to last post
  31. 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...

    Started by blacknumber2009‎, 10-10-2012 10:04 AM
    • Replies: 6
    • Views: 1,658
    10-10-2012, 10:46 AM Go to last post
  32. 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...

    Started by LMC2012‎, 10-09-2012 09:34 AM
    difference of proportions, lognormal, statistical test
    • Replies: 1
    • Views: 1,365
    10-10-2012, 08:02 AM Go to last post
  33. Question 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...

    Started by Trolle‎, 10-10-2012 04:36 AM
    chi square, fisher's exact test
    • Replies: 1
    • Views: 4,283
    10-10-2012, 05:55 AM Go to last post
  34. 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...

    Started by breez86‎, 10-10-2012 05:31 AM
    • Replies: 0
    • Views: 2,474
    10-10-2012, 05:31 AM Go to last post
  35. 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...

    Started by nyo‎, 10-09-2012 10:38 PM
    • Replies: 0
    • Views: 1,318
    10-09-2012, 10:38 PM Go to last post
  36. 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...

    Started by Jainie‎, 10-09-2012 09:50 PM
    • Replies: 0
    • Views: 2,974
    10-09-2012, 09:50 PM Go to last post
  37. 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...

    Started by Rekansha‎, 10-09-2012 06:55 PM
    odds ratio, risk ratio
    • Replies: 2
    • Views: 1,996
    10-09-2012, 08:27 PM Go to last post
  38. 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...

    Started by Badams‎, 10-09-2012 03:59 PM
    • Replies: 1
    • Views: 1,498
    10-09-2012, 04:37 PM Go to last post
  39. 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%...

    Started by Badams‎, 10-09-2012 02:45 PM
    • Replies: 0
    • Views: 2,063
    10-09-2012, 02:45 PM Go to last post
  40. 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...

    Started by ABCD‎, 10-02-2012 05:15 PM
    • Replies: 1
    • Views: 1,150
    10-09-2012, 01:44 PM Go to last post
  41. Who's a Gambler?

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

    Started by allan‎, 10-09-2012 04:23 AM
    • Replies: 5
    • Views: 1,781
    10-09-2012, 12:04 PM Go to last post
  42. First Time Trying To Build A Forecasting Model Using Regression. Need Help Badly!

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

    Started by erinwithane‎, 10-09-2012 09:31 AM
    • Replies: 0
    • Views: 1,001
    10-09-2012, 09:31 AM Go to last post
  43. Question 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...

    Started by Benedicta‎, 10-09-2012 05:39 AM
    • Replies: 0
    • Views: 3,709
    10-09-2012, 05:39 AM Go to last post
  44. (> 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...

    Started by allan‎, 10-09-2012 04:14 AM
    • Replies: 1
    • Views: 1,380
    10-09-2012, 04:16 AM Go to last post
  45. 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...

    Started by x509‎, 10-01-2012 11:19 PM
    population, sample, standard deviation, variance
    • Replies: 1
    • Views: 1,765
    10-09-2012, 03:52 AM Go to last post
  46. 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...

    Started by nyo‎, 10-07-2012 01:42 AM
    • Replies: 3
    • Views: 1,640
    10-09-2012, 02:29 AM Go to last post
  47. 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....

    Started by patman739‎, 10-08-2012 05:49 PM
    • Replies: 1
    • Views: 3,194
    10-08-2012, 06:09 PM Go to last post
  48. 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...

    Started by marika‎, 10-07-2012 02:57 PM
    • Replies: 5
    • Views: 2,032
    10-08-2012, 02:27 PM Go to last post
  49. 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...

    Started by Life_Learner_1‎, 10-08-2012 07:13 AM
    1:1, 1:m, analysis, continuous, matched
    • Replies: 4
    • Views: 7,758
    10-08-2012, 02:13 PM Go to last post
  50. 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...

    Started by drgunnar‎, 10-08-2012 10:13 AM
    • Replies: 1
    • Views: 1,750
    10-08-2012, 10:26 AM Go to last post
  51. 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...

    Started by drgunnar‎, 10-08-2012 08:24 AM
    • Replies: 4
    • Views: 1,224
    10-08-2012, 09:58 AM Go to last post
  52. 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...

    Started by kowalski‎, 10-08-2012 09:57 AM
    • Replies: 0
    • Views: 947
    10-08-2012, 09:57 AM Go to last post
  53. LSE of y = ax + bsinx

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

    Started by peripatein‎, 10-07-2012 08:25 PM
    • Replies: 1
    • Views: 1,145
    10-08-2012, 12:37 AM Go to last post
  54. 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...

    Started by trinker‎, 09-26-2012 01:42 PM
    formula, math notation, notation
    • Replies: 13
    • Views: 2,646
    10-07-2012, 10:25 PM Go to last post
  55. 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...

    Started by peripatein‎, 10-07-2012 08:18 PM
    • Replies: 0
    • Views: 1,488
    10-07-2012, 08:18 PM Go to last post
  56. Unhappy Please help! We've got lost in the wild jungle of T-TEST!

    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! ...

    Started by zerogreen‎, 10-07-2012 08:03 PM
    independent t-test, normality, paired t-test, t-test
    • Replies: 0
    • Views: 1,092
    10-07-2012, 08:03 PM Go to last post
  57. 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?

    Started by nyo‎, 10-07-2012 03:34 PM
    • Replies: 0
    • Views: 1,047
    10-07-2012, 03:34 PM Go to last post
  58. Smile Model building using Training data and predoction of Target set with test data

    Hi, Need some help to solve the problem using right s/w(SPSS or execl) and approach . I have a raw attribute data for 430 restaurants. ...

    Started by Mahendra‎, 10-07-2012 10:47 AM
    • Replies: 1
    • Views: 1,597
    10-07-2012, 01:48 PM Go to last post
  59. 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...

    Started by m_griffin007‎, 10-29-2008 07:51 PM
    • Replies: 4
    • Views: 4,431
    10-06-2012, 11:20 PM Go to last post
  60. age-heaping and running medians

    hello. i have a question about age heaping and running medians. i attached a excel sheet where i calculated running medians of 3,5,7 for ...

    Started by iIsee Deadpeople‎, 10-06-2012 09:47 PM
    • Replies: 0
    • Views: 1,444
    10-06-2012, 09:47 PM Go to last post

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