Choices can depend on the relationship between options, not just on each option in isolation.
ContestedReplications or meta-analyses disagree. Do not assume the effect.
Example
Adding an option with a higher price and fewer features may make a neighbor look attractive. The comparison labels this as an example to avoid.
Why it works
An asymmetrically dominated option is dominated by one alternative but not another. Experiments found that adding one could increase choice of the dominating alternative.
On the web
Give every plan an audience and a meaningful trade-off instead of inventing a dominated option solely to steer choice. Let users compare the features they need.
When it backfires
Results differ between numerical descriptions and perceptual or experienced attributes. Neither three options nor a middle price guarantees more choices; examine fit and later cancellation.
Sources
Shows cases where adding a dominated option increases choice of the option that dominates it.
Huber, Payne & Puto (1982). Adding Asymmetrically Dominated Alternatives: Violations of Regularity and the Similarity Hypothesis. Open source
Finds that attraction effects in numerical descriptions often fail with perceptual representations.
Frederick, Lee & Baskin (2014). The Limits of Attraction. Open source