An easy way of estimating single-stock beta

I submitted an earlier post about calculating Singapore Press Holding's beta using daily and monthly returns. I came up with some ridiculous beta figure.

I made a lot of mistakes in calculating the beta of a single stock against a larger market index and I'd like to post some corrections..

1. To calculate single stock beta use Microsoft Excel's '=slope('%change of stock returns', '% change of market returns')

2. The idea is that Excel's slope function measures the gradient of a curve. Here, the Y-axis is % change of stock returns and X-axis is the % change of market returns.

3. Beta is then defined as the 'change in Stock Returns' for a 1% change in Market Returns.

4. Note that you should compare like against like. Therefore, if you collect daily prices and then determine daily returns, plot it against the market indexes daily returns as well.