Margin Definition and 53 Threads

What exactly is a "margin of error" intended to be for a poll? Is it a one sigma number? A 90 or 95% CL? An educated guess? As I understand it, this number is reported on each result - i.e. if the poll says Smith and Jones each have 50% support with a 5% MOE, the "true" result can be anywhere...

1. One of the few negative effects of quitting smoking is weight gain. The data below shows the weight gain (in pounds) of 18 respondents 12 months after they quit. If the mean gain follows a normal distribution with a standard deviation of 9 pounds, estimate the mean weight gain of the 18...

WARNING: Topic is very pedantic. I have used a set of different physics books over the years, and they have all had a focus on the topic of significant figures, error margins and measurement. I have never quite understood these concepts fully and the relationships between them. One aspect I...

I need this in simple terms. Here's what I think I know so far (assuming 95% confidence level): MOE from a sample proportion is 2√(p(1-p)/n) and I think this is assuming the sample proportion is close to the population proportion. But then there is a sampling distribution of sample proportions...

Bounce 1, Trial 1-4: ha (height after bounce) (0.74+0.67+0.69+0.73)/4=0,7075 this is my mean value. Standard Deviation, s: 0.033040379335998 (calculated the value using an online standard deviation calculator) Sample size N: 4 sx̄ = s/√N = 0.033040379335998/√4≈ 0.0165 At a 95% confidence...

As a general rule of thumb what do you guys think is an ideal minimum safety margin when designing something? I know that this is a very broad question and could vary depending on the situation (ie something on a static load may need a smaller margin than dynamic) and since I do not have a...

customer buys 10,000 piece with cost of 0.20845 and sell price of 0.33621, what is the margin?

Hello, I have recently been given a job in Sales, and I really enjoy it. Math has never been a strong point and I struggle with percentages. I had an embarrassing experience the other day, where my manager jokingly asked me in front of everyone ‘If our product cost $100 and we want to make 50%...

Hello all, I have an interesting question regarding contribution margin (CM) % variance and how to attack it mathematically. If not known, contribution margin is defined as gross revenues minus all variable costs. This amount effectively shows how much money you have left to 'contribute' to...

Homework Statement Im going over some revision for fibre optics and I've come across an example question to calculate the power margin of the system with the following info is given: transmitter power = -10dBm Connector loss = 1.5dB Attenuation = 3dB/Km Total length= 2KM Receiver threshold =...

Homework Statement The Attempt at a Solution I am having trouble visualizing this. So I know that the phase margin is how much phase lag it would take to make -180 phase at the 0 dB gain frequency. I am just having trouble placing this on the plot. It isn't a homework question I am preparing...

It is said that the Madrid Spain solar chimney project occupies 110 acres land, but only output humble 50 kw: https://en.wikipedia.org/wiki/Solar_updraft_tower The fact: the average yearly solar power density of above powerplant = 0.11 W/m^2 Interestingly, there are many countries still...

Hi, How do I calculate the retail price for the following scenario: Retail price less a 20% commission less the cost of the product = a 15% gross profit margin (Gross profit margin percentage = (retail price - total cost (20% off of retail and cost of product)) / retail price I know what the...

I have a question regarding the time delay margin. I know the definition of time delay margin now I want to know that for the stability of the system is it good to have large time delay margin or small time delay margin?

Homework Statement Two components of a laptop computer have the following joint probability density function for their useful lifetimes X and Y (in years): f(xy)=xe^(−x(1+y)) 0 <= x <= y 0 otherwise Find the marginal probability density function of X, fX(x). Enter a formula below. Use * for...

When one types text in Word (Word 2010 on Microsoft), then obviously the text does not go below the bottom margin or above the top one. However, the Drawing Canvas (from Insert>Shapes>New Drawing Canvas) does not seem to respect these margins, not only going below or above the margins as one...

If each individual poll has a margin of error, when you combine all the polls, why do they say poll of polls has no margin of error? Shouldn't the margin of error get multiplied when you combine many polls?

Hey all I have one last question for you. I just need clarification on point estimate and margin of error as I have to find both in a problem. Let's say the endpoints are 5.9 and 8.1. When I do a margin of error problem, I subtract the mean of 7 from 8.1 right? When I do point estimate do I add...

Am I crazy (don't answer that) or what? Every article I read about the Daytona 500 race shows that Denny Hamlin nudged Martin Truex by .011 of an second. According to my calculation if you use 12 inches as the winning distance (could be 8 or 9) that would make their speed at the finish 61.983...

Homework Statement Find the Bode Plot, and the phase and gain margins for the uncompensated system. Homework Equations G = (3.6s+6)/(s(.1s^2+.7s+1)) The Attempt at a Solution I understand the phase and gain margin ideas, but the gain margin hinges on the phase crossing -180 degrees, and in...

Hi All, I am a rigger and it's my job to climb and be suspended from aluminum tube that is 4mm thick, for my new assignment. All of my fall arrest equiptment has to be rated for 22kn ( that's the load associated with a fall into a fall arrest device). The place I am working can't give me a clear...

I made this excel file that is basically a calculator. It needs to create a Total price after fees, profit and supplier cost. Most profit margin calculators have you add a percentage for profit... this is not what I want. I have a hard dollar amount. You must know that the entire transaction...

Hi, If I poll 10 people (with a yes/no question), and all of them respond with 'yes', should I report the rate of 'no' answers (in the greater population) is "zero plus or minus zero", or simply be confident that it is "less than one in five"? I ask because using the "margin of error" (or...

Homework Statement A Nyquist (polar) plot of a standard second-order system is shown below (drawn to scale). Suppose a unit-step function is applied as the input to this system. Determine the peak percentage overshoot expected in the system output. Homework Equations The Attempt at a...

I'm stumped at how to approach this problem and was hoping someone could enlighten me. If I had sold $100 of a product and made a 20% profit up until a specific day. The next day, made three sales; A) $20 making a $5 profit B) $50 making a $30 profit C) $30 making a $15 profit. So...

I have been debating with a few other people on another board, regarding the correct way to calculate the mean average of a list of values, where those values are recorded temperatures. A great many people seem to believe, for example, that if each temperature reading is accurate to +/- 0.5°...

N = 8 Mean = 2.10 stDev = 0.537 What size sample is required to construct a 95% confidence interval with a margin of error of 0.3? try n = 12, t(.975) with 11 deg. of freedom = 2.2001 so n = ( (.537* 2.2001) / (.3))^2 = 15.5 try n = 14, i get n = 14.95 n = 15, n = 14.74 Why is this a...

My question is: With a controller gain that meets the condition on the ramp set point, what is the largest achievable phase margin? I have no idea what the solution is saying! Does anyone know what this means exactly??

This picture is on a blank piece of paper but is rendered 2in below the margin. Why is this happening? I want it to be at the top of page right below the margin. The $z$ node is causing the problem. If I remove the $z$ node, the picture moves back to the top. What can I do about this...

Hi everyone here! I'm a LSA and PPL pilot, working on my CPL, and I have some questions to those who have knowledge of the aeroelastic effects and flutter phenomenon. I would like to talk a little about aerodynamic flutter onset speed and flight control malfunction. It is known that freeplay...

For a physics project, a few friends and I got ahold of a couple of balls that would record the time of an impact. Using this, we wanted to calculate g using kinematics to see how off we would be from the expected 9.81 m/s^2. Obviously, differences in altitude, air resistance, and experimental...

Homework Statement For x near 0, local linearization gives the following equation. e^x ≈ 1 + x Estimate to one decimal place the magnitude of the error for −1 ≤ x ≤ 1. Homework Equations The Attempt at a Solution I'm no exactly sure what to do here to be honest, but what I thought I'd...

Hello, I am trying to calculate what the margin of error for the standard deviation would be if each data point has a margin of error E. The standard deviation (for 3 data points) is defined as σ = \sqrt{\frac{(x_{1}-μ)^{2}+(x_{2}-μ)^{2}+(x_{3}-μ)^{2}}{3}} Where μ =...

Would it be possible to get the Transfer Function of a System if Open Loop Gain Margin and Phase Margin are known.

This is not a homework problem. I am working on an experiment and I need to know how many samples (n) I need to achieve a margin of error (e) below 2%. Looking through a statistics textbook they provide a calculation for e using z-distributions, but not t-distributions. Replacing...

For the Matlab bode diagram, normally when we want to obtain the gain margin, we have to cross the line from phase -180 and touch the curve. (Picture1 is what I did) however from the matlab, the gain margin crossover is start from -540 instead of -180 degree by using "Margin" function(Picture2...

Hi everyone, I'm not sure if this is the right section to post this in, but the question doesn't really seem to fit any singular category, so I'll try this one (if someone has a better recommendation, please let me know!) The question I'm seeking to answer is this: A baseband signal of...

I have been drawing a few bode diagram by hand and i am ask to find the phase and gain margin of the plot. Can someone please explain what are phase and gain margin, including how to determine it from the bode plot?

Revenue Equation: R(x)=-x^2+10x Cost Equation: C(x)= 4X+5 Average profit= profit equation, P(x)/x therefore p(x)= R(x)-C(x)=-x^2+6x-5 (-x^2+6x-5)/x=(-1(x-5)(x-1))/x, I then found that x is positive between 1 and 5, therefore average profit is positive in that range, however, the answer...

Hi, Just curious as to what is the basis of the margin of error given in polls, e.g., in statements of the form:" 30% of people are in favor of candidate x. The poll has a margin of error of +/- 5 %" Thanks.

Hello, I have the following question which I'm not quite sure about. I have the following Transfer Characteristic for a buffer. You can see the graph breaks at the points (2,0),(3.5,4),(5,5) http://img521.imageshack.us/img521/5052/captureen.jpg I need to set the appropriate values...

Hello All, I am having to brush up on my stats for work and it's been a long time (>10yrs) since I've had to even think about this stuff. I could do with some help clarifying a specific point about standard errors and margin of error. An example I am looking at from my old notes is this: the...

10 CFR 50.46 gives the acceptance criteria as the required condition for the performance of ECCS. There, it is indicated that PCT (Peak Clad Temperature) must be below 2200F. On the other hand one can rarely find an accident analysis for NPPs with the result of the analysis showing the PCT...

\int tan(x)dx with the limits of 0 to 1.55, with n=10. Using Simpson's Rule, my answer was 4.923651704. But I don't understand why Simpson's Rule varies from my calculator's answer (TI-84 Plus) which is 3.873050987. I thought the higher N with Simpson's Rule would make your answer even more...

Hi, I've been looking at some example solution and still haven't found the physical/mathematical explanation for the given solution. Problem: Due to slow satellite stabilization rotation there are big differences between maximums and minimums of received signals. Calculate the power...

I have seen in a few places around the web that the margin of error for the flatness of the universe is about 2%, but haven't seen any citations. Could anyone refer me to a reputable paper that I could cite that mentions what this margin of error is? Thanks!

Homework Statement I'm given a closed loop transfer function with a gain, K=1 and a plant H(s). I need to find the gain margin of the system. Homework Equations I know how to solve this problem: a) I find the frequency where the phase is -180 degrees. b) I find the gain at that...

Hello All, I have short edge margin condition of 1.36D on one of the part.Actually 3 parts of aluminum are joined together by bolts and one part has short edge margin. All the parts have sufficient bearing strength.So if I understand right bearing failure occurs before...

hi alll! just a quick one. You know when you design a controller - you go and plot the open loop transmission, L(jw) on a nichols plot, where L(jw) = C(jw)H(jw) P(jw) where P and C are the plant and controller respectively. You then 'manipulate' this plot (i.e. vary your controller) until...

hey guys. this has to do with determining the phase and gain margins of a system. i've read and understood the follwing: "To find GM, first find the phase crossover frequency, wGM. This is the frequency where the phase curve passes through -180. Get the magnitude at that frequency...