# err_vs_theta0_plot_for_homo_design: Plots a standard error estimate of thetahat (slope over... In optDesignSlopeInt: Optimal Designs for Estimating the Slope Divided by the Intercept

## Description

Plots a standard error estimate of thetahat (slope over intercept) over a range of possible theta0 values in order to investigate robustness of the the initial theta0 guess.

## Usage

 ```1 2 3 4``` ```err_vs_theta0_plot_for_homo_design(n, xmin, xmax, theta, theta0_min, theta0_max, theta0 = NULL, beta0 = 1, sigma = 1, RES = 500, Nsim = 5000, error_est = function(est) { quantile(est, 0.99) - quantile(est, 0.01) }, theta_logged = TRUE, error_pct = TRUE, plot_rhos = FALSE, ...) ```

## Arguments

 `n` The number of experimental runs. `xmin` The minimum value of the independent variable. `xmax` The maximum value of the independent variable. `theta` The putative true value. This is used to see how much efficiency given up by designing it for `theta0`. `theta0_min` Simulating over different guesses of theta0, this is the minimum guess. `theta0_max` Simulating over different guesses of theta0, this is the maximum guess. `theta0` The guess used to construct the experimental design. Specify only if you wish to see this value plotted. Default is `NULL`. `beta0` A guess to be used for the intercept. Defaults to `1`. `sigma` A guess to be used for the homoskedastic variance of the measurement errors. If known accurately, then the standard errors (i.e. the y-axis on the plot) will be accurate. Otherwise, the standard errors are useful only when compared to each other in a relative sense. Defaults to `1`. `RES` The number of points on the x-axis to simulate. Higher numbers will give smoother results. Default is `20`. `Nsim` The number of models to be simulated for estimating the standard error at each value on the x-axis. Default is `1000`. `error_est` The error metric for the estimates. The sample standard deviation (i.e. `sd`) is unstable at low sample sizes. The default is the 90 percentile minus the 10 percentile. `theta_logged` Should the values of theta be logged? Default is `TRUE`. `error_pct` Plot error as a percentage increase from minimum. Default is `TRUE`. `plot_rhos` Plot an additional graph of rho by theta0. Default is `FALSE`. `...` Additional arguments passed to the `plot` function.

## Value

A list with original parameters as well as data from the simulation