Validity is one of the most important criteria for the development and assessment of an instrument. Validity
refers to whether an item measures or defines a construct correctly. This study assessed both the content and
structural validity of the B-LAS. Scope validity refers to the extent to which the items cover the entire range of the
theoretical construct (in this case, the range of possible anxiety toward biology laboratory classes). Scope validity
was assessed first by expert review and then by the calculated correlation between the B-LAS and another test
known to measure a similar conceptual construct (Büyüköztürk, 2004).
Structural validity refers to whether the items are independent and evenly distributed, covering the intended
range of the construct. This was assessed with an exploratory factor analysis, a statistical technique that measures
the variance and accounts for it with the fewest number of structural factors (Büyüköztürk, 2004). Cronbach`s alpha
coefficient of internal consistency was used to assess the significance of the difference in item means between the
upper and lower 27th percentiles. Reliability of the instrument was also assessed with the item-total correlation by
split-half reliability and t-tests. SPSS 13.0 software was used for statistical analyses.