Ten statements, five response options, one score. The IPIP optimism scale looks simple enough to have been written in an afternoon, and almost every design choice in it is doing deliberate work — including the two items that appear to ask the same question twice.
Quick Answer: The scale is 10 public-domain items from the International Personality Item Pool with a reported alpha of .86. Six of the ten are reverse-keyed, so agreeing with everything produces a middling score rather than a maximum. The two "feel blue" items are an intentional reverse-keyed pair, not a duplication. IPIP items carry no licence fee and no permission requirement, commercial use included.
Why It Is Public Domain
The International Personality Item Pool was built as a scientific commons. Lewis Goldberg and colleagues described the project in 2006 as a response to a practical problem: the best-validated personality inventories were proprietary, and that slowed research down.
The pool's answer was to place its items in the public domain outright. There is no licence to sign, no fee, and no distinction drawn between academic and commercial use — which is why this scale can sit on a paid platform where several better-known optimism measures cannot.
What Reverse-Keying Is For
Six of the ten items are scored backwards: agreeing strongly earns zero, disagreeing strongly earns four. This is not a stylistic choice.
A scale where every item points the same direction rewards a habit rather than a view. Someone answering "very accurate" to everything without reading would score maximum, and their score would mean nothing. With six items reversed, that same habit produces a flat middling result — the pattern gets caught instead of rewarded.
A scale where every item points the same way measures how agreeable you are with statements, not what you believe about the future.
The Two Items About Feeling Blue
One item asks whether you seldom feel blue. Another asks whether you often feel blue. On first reading this looks like an editing mistake.
It is the reverse-keyed pair working as intended. Both items come from the source pool, and answering both the same way is precisely the inconsistency the design is built to detect. If you say you seldom feel blue and that you often do, the two scores cancel — which is the honest result for two contradictory answers.
What the Ten Items Cover
- Outcome expectancy. Whether you look on the bright side, expect to be a success, or see difficulties everywhere — the core of the construct as Scheier and Carver defined it.
- Baseline mood. How settled your general emotional weather is, which the pool treats as part of the same cluster rather than as a separate scale.
- Self-regard. Comfort with yourself, and whether life feels like it has direction — items that sit close to self-esteem and share variance with it.
That third group is why the score is best read as a general outlook rather than a pure forecast about events. It is measuring how you tend to see your situation, not only what you predict will happen in it.
What Alpha = .86 Does and Does Not Tell You
Cronbach's alpha measures internal consistency — how far the items behave as though they tap the same underlying thing. Above .80 is generally treated as good for a short scale, and .86 across ten items is solid.
It says nothing about whether the scale predicts anything in the world. That is validity, a separate question answered by separate studies. A perfectly consistent scale can consistently measure something useless, and reporting alpha as though it settled the matter is one of the commoner overclaims in test marketing.
Take the Scale
The Optimism and Pessimism test runs all ten items and returns a five-band result plus two subscale readings. If you want to see the same public-domain item pool at full length, the IPIP-NEO-120 measures the five broad factors from the same commons, and the Big Five test is the shorter route to the same map.