Standard deviation Definition and 271 Threads

I was given the averages (AVG) and the corresponding standard deviation (SD) of sets of data. I have no copy of the raw data for each data point that were used to calculate the AVG and SD. I performed further data treatment on the data. I want to ask what is the relationship between the...

Dear all, We were trying to solve the following question but did not quite understand what to do. The question is as follows: The reconstructed invariant mass is usually described by a Gaussian (or Normal) distribution. However, the resolution σ (the width of the distribution) is found to...

Homework Statement We performed an experiment to see which laboratory glassware was more accurate and which was more precise. Question: (a): Which glassware was more precise and why? (b) Which glassware was more accurate and why? Use the calculations to support your statement. I won't post the...

I'm trying to write a computer program which generates a random list of numbers but the random numbers form a bell curve, that is, there is a mean and a standard deviation from that mean. I'm not interested in some function that gets the job done, rather I'm trying to understand how do you...

Homework Statement For the five data 0, 7, 8, 10, and 10 find the standard deviation. Homework Equations https://forum.allaboutcircuits.com/threads/how-to-find-the-standard-deviation.138607/ I know the formula: Z = (X-Mew)/Sigma Sigma = Standard Deviation Mew = Mean = 7 X= score? Z= number...

Could someone guide me on the approach I need in resolving this question. I have seen some online examples of the same question, but what is required in this is different. I'll very much appreciate your support. Problem: For boys, the average number of absences in the first grade is 15 with a...

Homework Statement A company allows a maximum failure rate of 1 out of 250,000 parts. To insure this quality goal, failed parts must be how many standard deviations from the mean? Use Excel to solve. Homework Equations z= (X-μ)/σ The Attempt at a Solution Hi! So I'm assuming that this is a...

I have 2 signals: signal1: https://www.dropbox.com/s/zr04pff9skeh8cn/TX.dat?dl=0 signal2: https://www.dropbox.com/s/h436a915dd99hln/RX1.dat?dl=0 signal2 represents for 20 measurements, each measurement combines with signal1 to get time delay estimation using xcorr. So, I will have 20 delays...

My understanding of the distribution curves is very basic but I do have a couple of somewhat generic questions. I looked up a number of definitions but have had a hard time finding these specific answers: - Is there an agreed on minimum number of samples that one needs to take to deem a result...

Hey everyone! I'm learning about some statistics and its past office hours with my teacher but I'm stuck on this problem.. I came up with 2.14% as the probabillity\final answer.. Could you guys give me your 10 cents on this? Thanks again!

Hi Maybe my math/stat is very poor. I'm having trouble manipulating the standard deviation. Here's the thing. I have radar mounted on a car. For each detection, the radar returns these variables. - relative distance between the object/host vehicle in forward direction (in vehicle body-fixed...

I have a question regarding when to go for standard deviation σ or confidence interval ci. I am not sure of how to interpret ci. It seems to give me an option to choose the level of confidence, but I don't see why the the ci is divided by the root of the number of samples. Any pointers would be...

Hi all, I learn some statistics some times ago. It has been while but I still remember some characteristics and property of the normal distribution. One of them is the standard deviation could be used to estimated the probability of finding the entity around the mean in the range ##[-n\sigma...

I am trying to calculate the unit vector and standard deviation of the signal. I hope everyone can give me ideas. Here is my scenario: I have 2 rx channels: - f is channel 1 with the length 1x256 complex, then FFT. - g is channel 2 with the length 1x256 complex, then FFT. - from f and g, I can...

I just looked up the standard deviation formula. I makes quite sense to me because we're actually trying to 'measure' how much all the observations deviate from the mean value. To do this, we calculate all the possible differences, [X(mean) - x(i)], then we square all the differences to get rid...

Homework Statement Joan’s finishing time for the Bolder Boulder 10K race was 1.75 standard deviations faster than the women’s average for her age group. There were 405 women who ran in her age group. Assuming a normal distribution, how many women ran faster than Joan. Homework Equations The...

Homework Statement This is not homework. This is a question given in class with the answers already given. Neither the teacher nor the students have been able to figure out how to obtain the answers though, so my question is how to find them? Here is a picture of the question. The standard...

The King of the Hill triathlon race in Kinsale consists of a 750 metre swim, followed by a 20 kilometre cycle, followed by a 5 kilometre run. The questions below are based on the data from the 224 athletes who completed this triathlon in 2010. Máire is analysing data from the race, using...

Hello! I have some concentrical spheres with many points inside. And I need to plot the total mass of points in each shell (so between 2 spheres) versus the radius of that shell (defined as (r1+r2)/2, where r1 and r2 are the radius of the 2 spheres forming the shell). I have 10 shells so my plot...

I'm a beginner with the study in data analysis in Physics. I'm trying to understand the meaning, in the field of experimental Physics, of the standard deviation ##\sigma## of a series of data. There is one fundamental thing about ##\sigma## that I read but I could not understand. >In a series...

I´ve been trying to compute a volatility of invesment with currency hedging and I have a question. Let's take this example. We have our money in a fond copying the S&P500 index, which has 16% volatility, we also know that the current volatility of a dollar toward our currency is 5%. We want to...

Homework Statement I am given a numerical example (to be solved with pen, paper and calculator only) of an RBS spectrum of a AuAgCu-alloy on a glass-substrate. The question is "Can you get the composition? How accurate is the result?Homework Equations All the Rutherford Backscattering...

Find the standard score for a the data value 9 from a normal distribution which has a mean of 16.8 and a standard deviation of 2.3

Suppose i have a random variable X and its standard deviation dx. We could write the average with error like $$<X>\pm dx/2$$. But how do we know it is centered or not ? It could be +1/4 -3/4 for example.

In this homework question we are told to calculate the half-life of an isotope based on count-rates before and after a given time interval, the relevant equation is given below. Half-life = t1/2 = tln(2)/ln (A/A0) The second part asks to determine the standard deviation of the half-life due...

I was studying in my math textbook about these two methods to measure dispersion and variability in data. I was able to understand mean deviation that it's the average by how much a quantity deviates from mean but I was unable to understand standard deviation. Also, as standard deviation squares...

Hi everyone, I have a basic question on statistics. Suppose you have a biological assay to test a given property of some molecules. At some point in time you have tested N different molecules M1, M2, ..., Mi, ..., MN, and for each you have repeated the test a number of times Ri. The results are...

Homework Statement Find the formula for the standard deviation (s_h) of heading angle, given the north and east standard deviation of position of two points (s_n1, s_e2, s_n2, s_e2), each point's north-east covariance (s_cov_ne_1, s_cov_ne_2) and the north and east distance between them (d_n...

I did an experiment about interference of light when it passes two slits. I got datas and made chart, but I'm confused which result value I need to use whether % discrepancy or standard deviation. My data's & discrepancy is around 7, and difference between theoretical value and experiment value...

Any help would be much appreciated. The problem lies in the non-Gaussian distribution of the sample. If we take the entire data set of total fish catch, the skewness statistic equals 7.463 with a std. error of skewness of 0.39. Accordingly, the Z dist. (7.463/0.39)=19.14. Overall, the...

Any help would be much appreciated: My data is grouped into 42 categories according to classification of bird catch. Each group contains "X" amount of species, but for ease of input we categorize them into subsets. For example: Group 1: 265.5 kg Group 2: 47 kg Group 3: 213.5 kg etc...

I had a question about how to properly perform error analysis on a series of distance measurements. I need to find the relative error in the distance. I was wondering, should I use the instrument uncertainty divided by the measurement (in this case, it would be 0.005m / (mean measurement)). Or...

Hello, Upon following advice from BvU I'm starting a new thread to request help on a concrete issue I have. I have a container with 12x8 wells. Each well contains a roughly equal amount of bacteria. The bacteria are fluorescent, and I am trying to quantify their fluorescence as precisely as...

Homework Statement A business owner makes jars with weights that follow a normal distribution with a standard deviation of 8 pounds. In a random sample of 64 jars what is the probability that the sample mean differs from the population mean by no more than 1 pound? Homework Equations...

Hello, I have an experiment that I'm trying to conduct where I measure quantity A and normalize by quantity B. I then want to report normalized quantity A with error bars showing standard deviation. Quantity B is obtained via a standard curve that I generated (8 data points measured once each...

Hi, I've made a "probability" histogram for my data and it's based on 14000 datapoints in total, BUT each bin is not the same (e.g. bin 1 might be composed on 200 total datapoints while bin 50 is only 3 data points). You can find it in image 1. Now, based on those relative frequencies, I...

-3 SD -2 SD -1 SD 80 +1SD +2 SD +3 SD mean 65 70 75 85 90 95 The test has...

This is problem AP3.7 on page 669 of The Practice of Statistics, 5th AP Ed., by Starnes, Tabor, Yates, and Moore. A certain candy has different wrappers for various holidays. During Holiday 1, the candy wrappers are 30% silver, 30% red, and 40% pink. During Holiday 2, the wrappers are 50%...

When tossing a fair coin 1000 times a player correctly predicts 532 outcomes. Then I think I am right in saying that result is about + 2 Standard Deviations from the mean. sqr root 1000 x .5 x .5 = 15.81. 32/15.81= 2.02.However, if the results of the coin toss are given by a Net Gain/ Loss...

We have two groups measuring the same resistors, the nominal value is unknown. Group 1 is slower and because of that they did not calcute the s1 empirical standard deviation. Group 1: N1=500 , R1=6903 , s1=unknown Group 2: N2=20 , R2=6880 , s2=168.3 ,where N1,N2 is number of measurements...

Homework Statement I am stuck on the last problem. Homework Equations Just the error propagation equations The Attempt at a Solution I initially used the multiplication error propagation formula. So the average force would be the impulse divided by the time, the same thing as the impulse...

I'm trying to understand the derivation of the expression for the random Brownian force on a particle in a medium with coefficient of viscosity η. It turns out it is gaussian over some timescale, with a standard deviation that depends on the temperature and the viscosity. I'd like to read a...

Homework Statement "Consider a standard uniform density. The mean for this density is .5 and the variance is 1 / 12. You sample 1,000 sample means where each sample mean is comprised of 100 observations. You take the standard deviation of the 1,000 sample means. About what number would you...

I can get a measurement of my distance between points (x1,y1,z1 and x2,y2,z2) by analysing position data from a GPS/barometer system, which has a standard deviation of about 2m for x y z positions. I can also analyse data from a system that provides velocity with a standard deviation of about...

Given a one-dimensional Gaussian distribution, distributed as following: f (x) = exp (-x ^ 2 / (2q)) / q / √ (2pi) proof which q is the standard deviation Thanks !The standard deviation is defined by: http://www.mathsisfun.com/data/standard-deviation-formulas.html

I did the problem but none of my answers match up with the answer choices so I'm obviously doing it wrong. Can someone show me how to do these two problems. I have a test coming up and I am so behind For women aged 18-24, the systolic blood pressure (in hg mm) are normally distributed with a...

Say if I have a sample space 2,3, and 5. I want to find by what percent points deviate from the mean. So I would take the standard deviation as follows. 2+3+5 / 3 = 3.33 (2-3.33)^2 + (3-3.33)^2 + (5-3.33)^2 / 3 = 1.55 (1.55)^(1/2) = 0.775 So we get a standard deviation of 0.775. So how do I...

Homework Statement How does skew and range affect the standard deviation; does one affect it more than the other? Homework Equations None The Attempt at a Solution It seems as though if the range increases, the standard deviation increases because the SD is a measure of how spread apart...

hi (Wave) know its a big jump from calc 3 down to stats but i can't remember how to get the standard deviation. I am given this table and I am asked to find the standard deviation. can i please get a step by step solution? thanks (Blush)

Homework Statement There are 55 independent normal observations with mean 100. The first 50 observations have variance 76.4 and last five have variance 127. Calculate the probability that ##\bar{x}=\frac{1}{55}\sum_{i=1}^{55} X_i## is between 98 and 103. Homework Equations The Attempt at a...