The product backlog contains the product owner's assessment of business value and may include the team's assessment of effort or complexity, often, but not always, stated in story points using the rounded Fibonacci scale. These estimates help the product owner to gauge the timeline and may influence the ordering of product backlog items; for example, for two features with the same business value, the product owner may schedule earlier delivery of work with the lower development effort (because the return on investment is higher) or the one with higher development effort (because it is more complex or riskier, and they want to retire that risk earlier).