The Competitive State Anxiety Inventory-2 (CSAI-2) is the most frequently used instrument by researchers and practitioners for measuring competitive state anxiety in athletes.

CSAI-2 R (2003) is made of 17 statements that appraise 3 components: 1) cognitive Anxiety (e.g : I am concerned about choking under pressure ), 2) somatic anxiety (e.g : My body feels tense ) and 3) self confidence (e.g : I am confident of coming through under pressure ). Numerous studies have shown the psychometric validity of this tool.

The first version of the CSAI-2 vas published in 1990 [1]. Cox and colleagues published a revised version in 2003. This is the version currently available on Mindeval [2]. Researchers keep enhancing the CSAI-2, such as Terry and colleagues [3].

References:
[1] Martens, R. Vealey, R., & Burton, D. (1990). Competitive Anxiety in Sport. Champaign, IL: Human Kinetics
[2] Cox, R.H., Martens, M.P., & Russell, W.D. (2003). Measuring anxiety in athletics: The Revised Competitive State Anxiety Inventory-2. Journal of Sport and Exercise Psychology, 25, 519-533.
[3] Terry, P.C. Lane, A.M., & Shepherdson, A. (2005). Re-evaluation of the factorial validity of the Revised Competitive State Anxiety Inventory-2. In: ISSP 11th World Congress of Sport Psychology, 15-19, August 2005, Sydney, Australia. PDF