I have a series of data in excel in which a number of measurements over time is assigned to an ID X. Each X has different numbers of measurements and I am looking to find a way of returning the gradient of a linear regression for the measurements of each ID X vs time.
The dataset is arranged with a column for ID, a column for date, and a column for measurement value
At the moment I am carrying this out manually by scrolling down the list and calculating the regressions after selecting the measurements associated with a particular ID