# non-linear

1. ### Power function - finding if the slope is significant or not?

Hi, I'm using power functions to look at a relationship between time and age and I need to be able to test whether or not the slope of this relationship is significant or not. I am using SYSTAT, but cannot find out how to run this and produce a p-value. Is this not possible to test at all...
2. ### Non-linearity in OLS-Models, Multinominal Logit-Regression

Hey there, I have a question connected to the Ols-Model in case of nonlinearity between parameters. What should be done if the assummption of Linearity in OLS-Model ist not fulfilled and there is an non-linear relationship between the used parameters? And my second question is if I can use...
3. ### Multivariate logistic regression analysis from patient data

I would like to conduct a multivariate regression analysis on patient data using essentially the following setup: Dependent: a continuous variable Independent: several categorical and continuous variables. So I want to check whether any of the independent variable(s) predict the...
4. ### Cointegration in Non-linear time series

I have the following problem: In*non-linear time series regression yt = g(xt)+et, if xt is non-stationary (i.e. I(1)) and yt is stationary (i.e. I(0)), how to test that this relationship is cointegrated and not spurious? Would it be enough to use KPSS test for unit root on residuals et...
5. ### Testing for a non-linear (U-shape) relationship with 2 metric variables

Hi there, I have set up a hypothesis that I know want to test in SPSS stating that the relationship between X en Y is non-linear and takes a U-shape. Both the dependent as well as the independent variable are metric. How would I do this in SPSS? Thank you very much. Sophie
6. ### non-linear regression time response model

Hi I need to choose a non linear regression model for, protein phosphorylation over time response, for this kind of data Is not like enzyme kinetics, the michaelis menten model does not behave properly, becouse, I am not dealing with a susbtrate concentration, instead I got a signal...
7. ### non-linear regression

I'm a newbie to STATA and am trying to estimate a parameter using the 'nl' command. Here is the syntax: . nl (c1 = (c2^{a}-c2^{a}*y1^{a}/x1^{a}+y1^{a})^(1/{a})) The dataset has c1,c2,x1 & y1 given and I want to estimate a. However, I am getting the following error: "starting values...
8. ### Non-linear time series analysis

I´m looking for help to anlyse in R (or SAS) a non-linear time series dataset. I worked with six cows during three days and registered urine events of each cow during each day. I have 4 to 12 events for each cow and day that are non-equally spaced in time. I want to know if I have an...
9. ### Fit a non-recatngular parabola in R

Hello, I'd like to fit the formula below to a non-rectangular parabola in R. C = (XI+A-√((ϕI+A )^2-4XϕIA))/2X-R I have several data points that have values for both C and I. I have an estimate for X, A, ϕ, and R. So I'd like to use the estimates with each observation to get the fitted...