standard deviation

This is my homework question and in my right brained mind can not or the life of me think any further. My only hope is that someone out there in the universe can help my melted brain: Pick a continuous variable (that is, interval or ratio in scale of measurement) that is normally distributed...

Hello, In another post on SPSS forum I discussed Order effects where I split file on SPSS by order and conducted an independent t test looking at the effects of group on the DV. I found that the original result was only evident in order 1 and not order 2... however on the second order one...

I have the responses from a survey where people had to provide a rating on a scale from one to five, where five was most positive side of things. I would like to assume it is interval scale where the differences between each point on the scale are the same, as I would like to compute...

HI ! Excuse me for my english, my writing is not very good. I want to know what implies or what explains in an excercise when the standard deviation (STD=67) is higher than the mean (M=38), and the histogram behaves like an exponential distribution. Thanks by the way ! :tup: Regards from...

Covariance of two products I am in a stats class and the professor has asked us to calculate the covariance and the standard deviation of the total revenue. I was given the below information: X Unit Price = $10 E[X] = 10,000 Var(X) = 1,000,000 Y Unit Price = $5 E[Y] = 7,000...

I have reports based on long GPS occupations of the same site, which returns X Y and Z coordinates as well as the SD for each. I want the most accurate coordinates for the point as well as an estimate of the error/uncertainty. Attached are the XYZ and SD for 8 different reports of the same...

Hello, I was doing a practice test and I got two questions wrong. The answer key said that these two statements were false: As sample size increases, the standard deviation of the sampling distribution and the standard deviation of the population are increasingly similar. -and- For the...

Hi everyone I have a really basic question. I am displaying mean and standard deviation as a function of time by means of a line plot with scatter point circles representing the std. I am doing this for a number of different systems on the same graph so that they can be easily compared...

Hi, My goal is to estimate arrival times of buses at bus stops where historical GPS data for each bus is available and real-time bus location is available for each bus. What I would like to do is use the historical data to determine the mean time (in seconds) and SD taken for a bus to travel...

Hi guys, As basic as this question is, I'm looking for a way to calculate standard deviation of mean absolute error using pivot table or atleast using excel. I have fitted and predicted values. I calculated abs(y-yhat). and then when i used pivot tables i used "average" value to be...

Sorry for the basic question, I searched the internet but could not get a simple and clear answer. Application: I want to compute the std of a direction / bearing , values are from 0-360. I can convert the values into complex numbers and back to have a proper average. Question: Can I...

The z-scores from the 68-95-99.7 rule, which are 1, 1.96 (or 2), and 3 according to my textbook, arent matching up with the values i get if i try to find them using the Z-table in the appendix of the textbook. For example, the rule says 95% of the normal distribution falls within 1.96-2 std...

Hi all, I am experiencing difficulties to calculate portfolio volatility each period ("rebalance") given the following variables (enclosed). Correlation ("corr_Nt") across assets ("ticker") remains constant within a period. It is an equally weighted portfolio but weight changes each period (#...

I'm looking to analyse some data and as it's been a long time since my statistics days I'd like to know which area of statistics my problem lies. Lets say I have a number of different driving schools, each doing the same test of their student drivers' ability to have a licence. Now every...

I'm making a program which, at one point, is supposed to estimate the probability of having a certain disease based on the patient's age. I'm going to feed the mean age at which the disease occurs, along with the standard deviation, into the program, but I can't figure out how to actually...

Hello, I analyzed some physiologic data (blood electrolyte levels etc) which was fairly skewed, so I used Kruskal-Wallis to test for differences between groups. I originally plotted the mean and SD, but I learned that plotting the median is more suitable with skewed data. My question is...

Hi! I have 5 datasets each for 20 subjects which I have to plot relative to a baseline. To be more specific: Dataset 1: Contains mean value of the baseline condition Dataset 2-5: Contain each mean value of the conditions 2-5 Since this is the way I have to analyze these data, this is not...

I have a normal distribution of data with a mean of 0. I know that 80% of the data falls within 3 units of the mean. So 80% of the data is from -3 to 3. How do I figure out the standard deviation? It's been a couple decades since my last math class and I'm forgetting this stuff. Thanks!

I took a test for which the score range was 70-130. A score of 100 represents the average score of my peer group. The standard deviation was 15. My score was 105. I am wondering how accurate the test is, i.e. would a score of 100 in a hypothetical perfectly devised test be truly anywhere...

Hi, I am sorry of this stupid question :confused: I would like to know if it possible to calculate the standard deviation of a difference of means, having the two primary standard deviation and the two primary sample size and the two primary means. For example: I have 24 men that at T0...