Question

given a set of data of just one column. in excel or r please explain how to make this data (only has one column) into a ACF graph with their lags. only one data set was given with only one column. meaning there isnt a potential x and y columns. Please show code (if using R) or format if using Excel.

Answer 1

Autocorrelation is a major part of the study of time series. It allows us to understand how each observation is linked to its recent past observations in a time series. When autocorrelation in a time series is strong, predicting their future observations becomes easy.

We can also calculate the correlation between the actual series and the lagged series using the cor() function in R.

ACF Function

Instead of calculating the correlation with each time lag manually, we can use the acf() function in R. The function acf computes (and by default plots) estimates of the autocovariance or autocorrelation function for different time lags.

Below we get the autocorrelations for lag 1 to 10. Notice that the correlation keeps reducing as the lag increases.

syntax

acf(dataframe, lag.max=10, plot=FALSE)