Regression Definition and 324 Threads

Hi folks. Just looking for some input please. I have a dataset containing interval data (one dependent and 6 independent variables) and taken a random 90% sample (approx 300 observations). I've performed a linear stepwise regression on the 90%, in order to obtain a model to predict the...

Homework Statement http://www.math.tamu.edu/~vargo/courses/251/HW7.pdf Given a set of points (xi,yi) and assuming f(xi) is linear, the deviation measured is F(m,b)=\sum_{i}^{n}(y_i - f(x_i))^2. There are a few different questions about this from the link above. The Attempt at a...

urgent reply needed Can we use partial means as a predictor for the response while fitting a regression line or curve?.

Hi, I have a problem that is giving me a headache. I have measured two angles that I believe to be related to one another, and they are (this is a data set where I have measured the angle from a datum to two features on a bone. There are 14 bones in the data set): Angles to feature 1 (F1)...

I have couple questions about this and I was hoping someone with some stats knowledge could clarify. First, when people report numbers such as 10 plus or minus 5, what does the 5 mean? Is it the standard deviation or the confidence interval or the variance? What is the relationship between...

Homework Statement Using a data logger, I have collected data for two cooling cups: the temperature (c) at 1 second intervals. My task was to model this data using two methods. "METHOD 1: Use EXCEL or the regression analysis capability of your graphic calculator" "METHOD 2: Find the...

Homework Statement "You are asked to do an experiment where you will need to use a rotating blade to measure the wind speed. You measure the number of rotations of the blade at 10 different wind speeds, 10 times each and will make a linear fit to determine the wind speed as a function of...

What is a parameter regression in modeling?

Has anyone tried to apply the following regression equation appeared in the paper "Continuous measurement of systolic blood pressure using the PTT and other parameters" (Proceedings of the 2005 IEEE Engineering in Medicine and Biology 27th Annual Conference Shanghai, China, September 1-4, 2005)...

I'm not sure if this is the right place for this question, but it was on the comparison between different model's AIC/SBC values. I ran a linear regression and got an AIC/SBC of .743/.768. When I ran the same regression in log-linear form I ended up with an AIC/SBC of -7.559/-7.534. My...

I'm currently looking at a linear regression handout from Uni and there are two methods to calculate the equation. The Normal one is to find a and b for y=a+bx, the equations for a and b are given in the handout but I'll assume you're familiar with them. The simplified one is using y = Bx +...

Hey, so I've started doing a plasma physics research project and one of the things that I have to do is design a function which approximates a curve based on data points that its fed. So far I found the formula for creating a linear regression, but I'm having trouble finding the formulas for...

Hi all, I've learned that in unconstrained polynomial regression, the optimal order can be determined using two F tests : one to test for the significance of the overall regression, the other to test for the significance of the higher coefficients (assuming the first test passed of course)...

Hi all, I would like to understand the theory for determining outliers in the following scenario. Let's say I am to fit a linear model to the data of house size v. sale price for a particular location. And let's say I have a fairly good linear relationship, as house size increases, so does...

Hi there. I am having some trouble understanding the full context of this question. Suppose we have a categorical variable T E (1...n) and we observe k observations for Y when T = n. If a regression model holds: i) Write down Y in terms of dummy variables X1...Xi ii) What is the...

Consider the multiple regression model containing three independent variables y = B0 + B1x1 + B2x2 + B3x3 + u You are interested in estimating the sum of the parameters on x1 and x2; call this O1 = B1 + B2 a) Show that O hat1 = B hat 1 + B hat 2 is an unbiased estimator of O1. b)...

I am sooo lost in this class, please help. 1. Let the true (population) model be y = B0+B1x1+B2x2+u where u is an unobserved error term with u (conditional) x1, x2 and N(0, sigma^2). Hence, u is normally distributed with mean 0 and variance sigma^2 (i.e., E[u (conditional) x1, x2] = 0 and V...

Hi everyone, This is not a homework question. I just want to understand an aspect of linear regression better. The book "Applied Linear Models" by Kutchner et al, states that a linear regression model is of the form Y_i = B_0 + B_1 X_i + \epsilon_i where Y_i is the value of the...

Hi, I have the following population figures for a five year interval: 554.8, 609, 657.5, 729.2, 830.7, 927.8, 998.9, 1070, 1155.3, 1220.5 The graph has an exponential growth from the first value to the fourth value and then the population starts to decay. I found that a Cubic...

I've been told that their exists no perfect mathematical method of obtaining a line of best fit from a population of data. This doesn't make a whole lot of sense to me, so I have made an attempt at doing such (see google docs link)...

Dear all, let's say I want to know the elasticity constant of a spring (k), so I measure several times different values for the force applied to the spring, F, and the displacement of the spring, x. So, for N measures, I have xi and Fi and their uncertainties. Now, I'm really not an expert of...

Statistics, multiple choice, regression equation -- 2nd question Homework Statement A regression equation was developed to predict gasoline mileage (mpg) for various car weights (pounds). The resultant equation was: Y = 35.2 - .0034 X. Which two answers can be concluded? A. The...

Statistics help -- Scatter plot, regression Homework Statement Consider the following data set for ten first grade students; the variables are the number of minutes spent learning a list of spelling words and the number wrong on the spelling test. [15 points total] (supposed to be a...

Hi friends, I need to get the surface equation like function f(x,y) that passes through 66 points. I attached the file xls where is the points, and a pdf file where is the graphics of the points. Can somebody help say me that I have to do for solve it?

Homework Statement given the regression of y on x is 2y-3x=10 and the regression of x on y is 4x-3y=8 find the correlation r between x and y, also find the mean of x and the mean of y. Homework Equations The Attempt at a Solution I am absolutley clueless on this problem, there is...

Trying to translate a mathematical term from Hebrew to English ("regression rule") If I translate it word by word in Hebrew, it's the "regression rule" Such as, I am told that "a series is defined for every natural n by the regression rule"...

Hi y'all, wondering if you could help me with this. I have a data set with a linear relationship between the independent and dependent variables. Both the depended and independent variables have error due to measurement and this error is not constant. For example, {x1, x2, x3, x4, x5}...

I've been trying to figure out how to do a linear regression on data with asymmetric x and y error bars (different for each data point). Any help would be much appreciated.

I have a very small set of data. Usually 3 points, sometimes 4. Best fit is a logarithmic equation y=m*Ln(x)+b How can I obtain m and b?

Homework Statement [PLAIN]http://img822.imageshack.us/img822/4421/statsii.jpg The Attempt at a Solution Done parts (a) and (b). How do I do parts (c) and (d)? Is the simple linear regression model just Y_i=\beta_0+\beta_1 X_i + \varepsilon_i where \varepsilon_i \stackrel...

Hello. Can anyone tell me what would be the best software to use for the nonlinear regression? I have an equation with two unknown parameters which I would like to find out. Equation looks something like this: f(x)=a*b*x/(1+b*x), where x and f(x) are known (several points) and I would like to...

In the least square linear regression, say we have y=Xb+e (y,b,e are vector and X is matrix, y is observations, b is coefficient, e is error term) so we need to minimize e'e=(y-Xb)'(y-Xb)=y'y-y'Xb-b'X'y+b'X'Xb we can take the derivative of e'e to b, and we can get the answer is 0-2X'y+2X'Xb...

I want to do multiple linear regression, but one of the requirements is the residuals to be normally distributed, and I can check that with QQplots but then the QQ plot shows it is about 95% of data fit into the normal line, but 5% is way off! can I still proceed ?*or do I have to find a way...

If someone is interested in modelling data on households to find out whether there is discrimination in the workplace why would they ever leave out variables which are relevant to explaining the dependent variable but not so relevant to the investigation? e.g. let's say they survey age, race...

To determine whether schools are increasing the amount of students meeting or exceeding standards, I obtained a MEAP database reporting the amount of students that scored in the met or exceed standards range during years 2005-2009, for grades 3-5. I then graphed the data for using numbers...

Does anybody of you know about this problem and how to compensate for it?

Hello all; I'm doing work for my job, and I've forgotten my statistics =(. I first want to know if what I'm trying to do is possible. I want to create a linear regression of the form Y = a * x1 + b * x2 + c. http://imgur.com/Q4vGP" As you can see, there is space that is grayed...

Homework Statement Where can I find Y(subscript: 1) on the TI-83 plus calculator? I was working on Linear Regressions in the book and I came across a question that requires me to input Y1 on the screen but I can't find the 'y'.. how can I find it? Homework Equations The Attempt at...

Homework Statement http://img683.imageshack.us/img683/4744/leastsquares.jpg [PLAIN][PLAIN]http://img149.imageshack.us/img149/4793/graphwd.jpg Homework Equations The Attempt at a Solution So would these be the points? (-41,51),(-22,62),(23,63),(44,24) I'm not too sure how...

I am not sure if Multiple regression is what I want. I essentially have a function Y that is a function of three independent variables. I have a collection of points which have given Y-outputs. So when given the inputs (1, 30, 60), Y = 5. When given (1, 30, 210), Y=8. When given (2, 70...

Hi guys, I have data of 20 peoples height, weight, calorie intake and skinfold thickness. I have carried out a regression of calorie on height, on weight and on height and weight. I have done the same thing for skinfold thickness. I then used R to work out the summary of results. each...

I have a model y= beta0 + beta1 x1 + beta2 x2 + eps, eps~N(0,1). How to test hypothesis beta1=0 ? Is the same test for beta2=0?

Hi I've been tasked with making a sort of sensitivity analysis tool. The goal was to get as many parameters as possible and then use them to build a model that would allow users to change variables a bit and see what happens to the one dependent variable. So I used a multi variable...

Hello, In simple linear regression (or even in multiple linear regression) how does one prove that the coefficient of determination, given by R^2 = \frac{SS_{Reg}}{SS_{Total}} = 1-\frac{SS_{Res}}{SS_{Total}}= 1-\frac{\sum_{i=1}^{n}(y_i-\hat{y}_i)^2}{\sum_{i=1}^{n}(y_i-\overline{y})^2} is...

Hi All, Hope this is the right sub-forum for this. I currently work for an engineering consultancy and am doing some project management what for what are essentially site investigation reports (sites are quite small, typically a few acres/hectares). Our clients are mostly developers who have...

I am trying to figure out how to combine uncertainty (in x and y) into the standard error of the best fit line from the linear regression for that dataset. I am plotting units of concentration (x) versus del t/height (y) to get a value for the flux (which is the slope) I understand how...

Hi: This is my first post and I'm not sure if this is the right forum. Please redirect if necessary. I'm new to nonlinear regression, but from what I've read I realize that making "good" initial guesses for the model parameters is very important, otherwise a "best fit" may not result...

I'm attempting to solve a multiple regression. My problem is that I want the resultant function to be always positive. I need a regression of the machining cutting force for several values of cutting parameters (cutting speed, depth of cut, ...). The cutting force has to be always positive...

Homework Statement I'm new to uncertainty, so I needed a little assistance. The circuit in this experiment was simple, a dry cell connected to a variable resistor. I used an ammeter on the circuit and used a voltmeter across the resistor and took some measurments. The experiment was to...

Homework Statement convert a*sin(bx+c)+d to (mx+d)+a*cosb(x-c) Homework Equations The Attempt at a Solution