| Subject | Date Asked | Expert |
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| percentage question (if several times) | 5/21/2007 | Joe Engels |
Q: I would like to know the overall percent I would have if I have a 30% chance each time. I would ...
A: If I am understanding your question correctly, this is similar to flipping a coin. For example, The ...
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| Simple survey concepts help | 5/15/2007 | Ellis Godard |
Q: Ok, so if I wanted to design a survey/questionnaire, I can report what my sampling size should be ...
A: The confidence level (e.g. 90%, 95%, 99%) could be the same for the entire survey, although there ...
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| PD | 5/1/2007 | Joe Engels |
Q: Probability distribution formula. I need help sorting it out. The demands are: 0, 1, 2, 3, 4, 5, 6; ...
A: The expected number per day is calcualted by: ...
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| predicting future losses | 4/30/2007 | Ellis Godard |
Q: I've been asked to develop projections for the number of people my organization anticipates losing ...
A: I don't think linear regression is what you want, for two reasons: First, that would require an ...
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| Project research question | 4/22/2007 | Ellis Godard |
Q: This is not a homework problem. Im working on a statistical project. Suppose i have a rubberband, ...
A: I would suggest, for each point, (1) summing the squared distances to the other points before ...
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| problem solving | 4/18/2007 | Ellis Godard |
Q: You have 8 golf balls, seven of which weigh exactly the same. The eighth golf ball weighs slightly ...
A: First put 3 on each side of the scale. If they match, put one of the other two on each scale and see ...
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| probability | 4/16/2007 | Soroban |
Q: another question that follows from my last, there was two bags the first with 4red & 6green, and the ...
A: Andrew! "In warehouse A, 40% of the potatoes are rotten. In warehouse B 30% of the potatoes are ...
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| math | 4/16/2007 | Soroban |
Q: one study indicates that 5% of men and 0.5% of womwn are colorblind. find the probility of choosing ...
A: dillon! The problem is not stated clearly. They ask for the probability of choosing a colorblind ...
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| probability and statistics | 4/15/2007 | Ellis Godard |
Q: how can I find a z critical using the critical value approach?
A: There's probably a table in the back of your text book, and it's probably Table A. Look there for a ...
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| probability | 4/15/2007 | Soroban |
Q: another question that follows from my last, there was two bags the first with 4red & 6green, and the ...
A: Andrew! This is a conditional probability problem which requires Bayes' Theorem. P(bag #1 | ...
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| probability | 4/15/2007 | Soroban |
Q: there are two bags one bag contains 4 red disks & 6 green disks, the other bag contains 7 red disks ...
A: Andrew! Your answer is correct . . . good work! Prob. of choosing bag #1 is 1/2. Prob. of getting ...
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| Statistics | 4/12/2007 | Ellis Godard |
Q: I am a wellness coordinator at a college and am looking to put together a wellness program based on ...
A: Yes. You'd want to examine results (whether OLS/GLM, logit, whatever), remove variables with ...
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| probability of choosing 2 like items | 4/11/2007 | Soroban |
Q: My daughter asked my help with this and I cannot recall how to do this. I had a lot of math but ...
A: Renae! Since there are 6 socks among the 10 socks, the probability that the first sock is ...
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| statistics | 4/10/2007 | Joe Engels |
Q: I am a wellness coordinator at a college and am looking to put together a wellness program based on ...
A: Hmmm...tough question. Absenteeism rates should be fairly easy since this data is probably readily ...
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| Probability-Dice Question | 4/9/2007 | Soroban |
Q: A fair die is rolled 10 times. what is the probability that an even number (2,4,6) will occur ...
A: Octavia! This is not a simple problem. I hope you are familiar with Combinations and Factorials. ...
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| Proportion, percentage and ratio | 4/6/2007 | Soroban |
Q: What are the differences among a proportion, a percentage, and a ratio?
A: Tracey! A proportion and a ratio are almost the same, and are often (and easily) confused. If ...
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| estimated output | 4/6/2007 | Joe Engels |
Q: i have estimated a regression for cross-sectional time series pooled data. the results, i obtained ...
A: By inserting AR(1) to account for lags in the data, I would guess your second regression is correct ...
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| estimated output | 4/6/2007 | Joe Engels |
Q: i have estimated a regression for cross-sectional time series pooled data. the results, i obtained ...
A: Well, In order to help further, I will need to see your data. What type of regression was completed? ...
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| 2 quick questions | 4/5/2007 | Joe Engels |
Q: If a team makes it to the NCAA tournament how do I figure the probability of them winning it? I ...
A: If a team makes it to the NCAA tournament how do I figure the probability of them winning it? If ...
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| Poker, Luck and the Bell Curve | 4/4/2007 | Ellis Godard |
Q: The consensus in Poker seems to be that in the long run "luck" will even out for everyone, and by ...
A: I'm not sure whom you've heard or read who thinks that poker is a game of luck, but that wouldn't be ...
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| Paired t test | 4/3/2007 | Joe Engels |
Q: I am testing moisture content in wood samples using two different methods; an oven dry weight test ...
A: When we run a t-test, usually you setup a hypothesis, such as: Ho: Dry wt test = Surface Meter Ha: ...
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| Psych Stats | 4/3/2007 | Joe Engels |
Q: I did a t-test on SPSS. It gave me all of the reults. Now i need to answer the question How ...
A: If a result is statistically significant at the p=0.05 level, this means that if we repeated the ...
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| Statistical projections | 3/28/2007 | Joe Engels |
Q: I've been asked to develop projections for the number of people my organization anticipates losing ...
A: I would use a regression equation which finds a linear relationship between year and lost employees. ...
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| probability | 3/25/2007 | Soroban |
Q: In a class of 22 students, there are 15 males and 7 females. If a committee of three is randomly ...
A: Catherine! I will assume you understand Combinations. There are C(22,3) = 1540 possible ...
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| Choosing a test | 3/25/2007 | Joe Engels |
Q: I am trying to choose a statistical test, after gathering my data (not the smartest move, but ...
A: The more I think about it, maybe you should not use a paired T-test. Use a t-test assuming unequal ...
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| Choosing a test | 3/25/2007 | Joe Engels |
Q: I am trying to choose a statistical test, after gathering my data (not the smartest move, but ...
A: OK, now I get it... I would do a t-test comparing the mean scores of the 2 highly attractive first, ...
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| stats | 3/10/2007 | Joe Engels |
Q: you have been very helpful. i have one more question. in a certain flock of 130 geese made up of ...
A: We know that 58 of the 130 geese are banded. 36 of them are banded canadian geese, so that leaves ...
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| lottery | 3/6/2007 | Joe Engels |
Q: I have seen shows on TV where it has been stated that it doesn't matter how many tickets you buy; ...
A: Yes. The reason being...if you buy 1 or 1000 tickets, each ticket has the same exact probabilty of ...
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| Quartile | 3/4/2007 | Joe Engels |
Q: A financial advising company has determined that the price to earnings ratios for 20 randomly ...
A: The third quartile cuts off the top 25% of the data. For your example Since you have 20 data ...
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| sample | 2/28/2007 | Joe Engels |
Q: The estimate of a population porportion is to be within plus or minus .05, with a 95% level of ...
A: To find sample size when tryinh to estimate a population proportion, we use this formula: n = ...
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| sample statistics | 2/25/2007 | Joe Engels |
Q: can you explain the equation that you used. [(1.96)(10)]^2/2You are testing a level of chemical. ...
A: the equation used is: n = (Z(alpha/2) * Std Dev)^2 ----------------------- E n = ...
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| sample statistics | 2/25/2007 | Joe Engels |
Q: You are testing a level of chemical. From past experience, you know that it can be modeled by a ...
A: We are solving for sample size n. A 90% confidence level corresponds to alpha = .1 Alpha/2 (for ...
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| Mean | 2/23/2007 | Joe Engels |
Q: The mean of a normal probability distribution is 60 and the standard deviation is 5. What percent of ...
A: One standard deviation would be +/-5 Two standard deviations would be +/-10 So, +/-10 would be 50-70 ...
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| which tests to use | 2/22/2007 | Ellis Godard |
Q: I am comparing accredited and non-accredited institutions by looking at 6 variables: 1) state ...
A: Selection of the test, and of the descriptive statistic (mean, median, or mode) that it tests, would ...
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| rmANOVA vs ANCOVA | 2/20/2007 | Joe Engels |
Q: The website you suggested is very useful, but as we explained, we are interested in repeated ...
A: I'm sorry about that. Let's see... One-way repeated measures ANOVA compares how a within-subjects ...
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| Logistic regression | 2/19/2007 | Joe Engels |
Q: My question is regarding the validity of my independent variables. I have female choice data and ...
A: It looks like your data is setup more for a chi-squared test rather than a regression. Using ...
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| Projected death rates | 2/16/2007 | Joe Engels |
Q: Sorry for the morbid subject matter. I have a problem I wonder if you can help me with. I work in ...
A: Unless you are using a model, there are many factors that go into calculating life expectancy. I ...
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| statistical data | 2/13/2007 | Joe Engels |
Q: the yearly data is just a flow of immigrants coming into the country. it is the total immigration ...
A: Ok, I understand. Lets say the total immigration index is like 25,023 and the unemployment rate is ...
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| statistical data | 2/12/2007 | Joe Engels |
Q: I have now only monthly data and not quarterly. i have monthly data on unemployment and wage ...
A: Take your monthly data, for instance, lets say you have jan, feb, and march...add all three months ...
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| statistical data | 2/12/2007 | Joe Engels |
Q: however i need to regress a model and i need all frequency types to be the same. Preferably i would ...
A: This is kind of difficult. The only way this can be done is to really scrutinize your quarterly ...
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