Table of Contents

Sample: IntroBenchmarkBaseline

You can mark a method as a baseline with the help of [Benchmark(Baseline = true)].

Source code

using System.Threading;
using BenchmarkDotNet.Attributes;

namespace BenchmarkDotNet.Samples
    public class IntroBenchmarkBaseline
        public void Time50() => Thread.Sleep(50);

        [Benchmark(Baseline = true)]
        public void Time100() => Thread.Sleep(100);

        public void Time150() => Thread.Sleep(150);


As a result, you will have additional Ratio column in the summary table:

|  Method |      Mean |     Error |    StdDev | Ratio |
|-------- |----------:|----------:|----------:|------:|
|  Time50 |  50.46 ms | 0.0779 ms | 0.0729 ms |  0.50 |
| Time100 | 100.39 ms | 0.0762 ms | 0.0713 ms |  1.00 |
| Time150 | 150.48 ms | 0.0986 ms | 0.0922 ms |  1.50 |

This column contains the mean value of the ratio distribution.

For example, in the case of Time50, we divide the first measurement of Time50 into the first measurement of Time100 (it's the baseline), the second measurement of Time50 into the second measurement of Time100, and so on. Next, we calculate the mean of all these values and display it in the Ratio column. For Time50, we have 0.50.

The Ratio column was formerly known as Scaled. The old title was a source of misunderstanding and confusion because many developers interpreted it as the ratio of means (e.g., 50.46/100.39 for Time50). The ratio of distribution means and the mean of the ratio distribution are pretty close to each other in most cases, but they are not equal.

In @BenchmarkDotNet.Samples.IntroRatioStdDev, you can find an example of how this value can be spoiled by outliers.