Development and validation of a structured observation scale to measure physical activity instructors’ need-supportive and -thwarting strategies

Abstract

Problem Statement: A key challenge for every physical education teacher is motivating students to participate. Instruction is an essential motivational tool within a teacher's pedagogical toolbox. From this instructional standpoint, a central question is which strategies most effectively support participant motivation. Given the practical need to accurately evaluate the impact of these strategies and the growing number of experimental studies on psychological need-supportive instruction, reliable and valid scales to measure need-support are essential. Purpose: This study aimed to develop a need-supportive and -thwarting instruction observation scale (NSTI) and perform psychometric testing of the scale. Approach: A sample of 20 physical education classes and 540 observations consisting of 110 college-aged students were recruited. Results: First, the content validity was established by using the Delphi method followed by the steps to establish factorial and construct validity. Between-rater correlation (.80 to .95) suggested strong internal consistency. Factorial validity was excellent, factor loading ranging between .88 and .99, with 92% (CI 95% [.89, .95]) of the total variance explained. Several factor solutions were tested. Confirmatory factor analysis supported the one-factor solution (χ2(27) = 35.45; CFI = .99; TLI = .99; RMSEA = .07). Conclusions: In conclusion, NSTI had a desired validity and reliability to measure instructor’s need-supportive and -thwarting behaviors in physical activity. This study fills an important gap in Self-Determination Theory-centered literature and represents an advancement of the literature focusing on how to measure need-supportive instruction in physical activity validly and reliably.