deviation

1. Standard deviation on scaling of random variables

I have the answer already (based on simulations), but want to know exactly which theorem/ law is at play: Suppose X1, X2, X3, X4 are 4 positive random variables such that X1+X2+X3+X4=1. Suppose I scale them with known constants C1, C2, C3, C4, respectively, then look at the function below...
2. Mean of means - standard deviation of mean values

Sorry if this has been asked numerous times and sorry if I describe it from an engineers point of view. Let us say I have N measurements and I calculate the mean value and the standard deviation. Okay. Now let us have M times N measurements. I could calculate now the mean value of the whole...
3. Criticism of the Standard Deviation

Standard Deviation is widely used to measure risk in assets. I think a higher standard deviation is considered a risky bet, with greater upside and downside potential. However, if the asset A's returns are: 50, 50, 50, 400 and Asset B's return are 50, 50, 50, 50 -- the latter will have much...
4. Confidence interval for the population standard deviation?

Use the given degree of confidence and sample data to find a confidence interval for the population standard deviation. Assume that the population has a normal distribution. The hockey coach selected eight players at random and timed how long each player took to finish their exercises. The...
5. Why use variance instead of standard deviation?

This drives me crazy, The question is simple: A manufacturing process has the expected value of 200minutes and standard deviation of 10minutes The reset process has the expected value of 30 minutes with the standard deviation 3 minutes Compute the probability that the sum of the...
6. Manipulate data to match given mean and standard deviation

I have a set of data with a mean of 55.05 and a standard deviation of 7.51. However, I want to transform these data to a list of values with a mean of 55.62, a standard deviation of 58.69, and the list should not contain negative values. Is this possible? Thank you The list of data is below...
7. Find standard deviation given normal probability

I have $X \sim N(0,\sigma^2), Y \sim N(-1,4) \mbox{ independent}, \\ Z = X-Y$ find $\sigma$ such that $P(Z \le 7) = 0.84134$ what I have done is : $X-Y \sim N(0-(-1), \sigma^2+4) = (1, \sigma^2+4)$ \$\begin{array}{lcl}P(Z \le 7) & = & P( \frac{Z -1}{\sqrt{\sigma^2+4}} \le...
8. Standard and standard deviation

Hello :) I have 2 questions which i didn't succeed to solve them, I don't even have a direction, so can you help me please? The following given refers to 2 questions - The standard is that the weight of a cheese should be between 94 to 106 grams. 1. The industry produces cheeses, the...
9. Which of the two sets of data intervals has the greater standard deviation?

A company is evaluating two employees' times to complete the same repetitive task. Employee A's time and frequency Under two minutes: 2 2 to 3.99 minutes: 6 4 to 5.99 minutes: 9 6 to 7.99 minutes: 2 8 to 9.99 minutes: 1 Employee B's time and frequency Under two minutes: 3 2 to 3.99 minutes: 5...
10. One measure significant in standard deviation?

When is one observation not considered statistically significant, such as subtracting one (Bessel's correction) while calculating standard deviation?
11. Why is my Standard Deviation larger than the mean?

Hello, I have an assignment asking me to calculate the mean and standard deviation for Weekly housing cost. All of the data came from 306 students who filled in the survey. I was given raw data in excel. I used excel to calculate the mean by typing '=average(' into the formula bar and...

13. Skewed Deviation

Hi All, Hope you're all well. in excel, I am using 2 input parameters; average and standard deviation, and generating a set of 1000 lines using the random function. currently i have to avg set to 4.5 and stdev at 2. =NORM.INV(RAND(),4.5,2) i produce a graph and you can see a normal...
14. Large deviation function for a Gamma distribution

I have a problem with the final part of this exercise. I have computed the large deviation function of that distribution correctly, I've also found the form of the Y function but I'm not able to justify that relation. Could anyone explain it to me please? Compute the large deviation function...
15. Is it normal if deviation is greater than variance?

Here is my problem, a sample of 7.55, 6.13, 5.44, 7.19, 6.33 My answer is mean = 6.528 sample variance = 0.716 and deviation = 0.846 but i was told that variance is always greater than deviation, so i am confused now.
16. Determining Deviation Scores

Hi all! I'm Stuck with this one. Would really appreciate your help with this... :cool: The values of three out of a sample of four deviation scores are: âˆ’5, 2, and âˆ’3. The value of the fourth deviation score is
17. Standard Deviation

What is approximate standard deviation for the list of numbers: 10.4, 9.8, 10.0, 9.2, 10.5, 9.8, 9.9, 10.1, 10.4, 10.2, 10.7, 9.6? A. 2.1 B. 1.9 C. 1.75 D. 1.8 The question shows up on my kid's test recently. The standard deviation is 0.42. Why can the answer be C. 1.75? If 0.42...
18. Dividing Standard deviation by sqrt(n)

Hi all, I've been arguing with a mate about a thing he calls Real Standard Deviation. What he does is siply dividing the standard deviation of a set of data by the square root of the number of observations, n. Now, I myself couldn't find any information about it on google, and can't really...
19. Average Mean Deviation VS. Standard Deviation

Average Mean Deviation, to me, has a much more intuitive meaning than Standard Deviation. Truthfully, I'm not even sure why we use Standard Deviation. I suppose that's where my statistics class failed me. Anyway, I have a few questions: Why isn't average mean deviation taught in...
20. probability of getting a deviation of 43% from expected value after 3594 trials?

In a lottery game with 8 different combinations, what is the probability of winning at least 642 times if playing 3594 independant and separate lotteries and each lottery choosing 1 combination? In other words, what is the probability of getting such a huge deviation to the Law of Large Numbers...