A person’s academic achievement level affect many aspects her life. Though there are numerous factors affecting a person’s academic achievement level, those factors can be classified either as a personal factor or as an environmental one. Personal factors explaining academic achievement can be further divided into either cognitive or non-cognitive one. During the past 30 years, research community has focused its attention mainly on highlighting the effect of cognitive factors on one’ academic achievement. Recently, an increasing number of studies have reported that non-cognitive factors such as motivation, attitudes, self-concept, level of aspiration affect one’s academic achievement as much as cognitive factors. Grit, referred as a 21st century skill, is a good example of non-cognitive factor that affects academic achievement. Grit is a personal characteristic that makes one keep her passion and perseverance for long-term goals. As grit is a newly introduced construct, we still do not understand its relationships with other variables very well. In particular, we have very scant knowledge of factors that affect grit. Finding out what factors affect grit will not only clarify the concept of grit itself, but it also will help us in utilizing the concept to improve training and education. According to the implicit theory(Dweck et al., 1995), locus of control and mindset can be possible factors affecting grit. However, I could not find any prior study that investigated the relationship. Thus this study investigated if locus of control and mindset affect academic achievement through the grit as a mediator factor.
The Purpose of this study is to identify a causal relationship among locus of control, mindset, grit, and academic achievement with the method of structural equation modelling.
The specific research questions are as following; Does locus of control have direct effects on grit? Does mindset have direct effects on grit? Does mindset have direct effects on academic achievement? Does grit have direct effects on academic achievement? Is grit a mediate factor effects on the relationship between locus of control and academic achievement? Does grit have mediator effects on the relationship between Mindset and Academic achievement?
To accomplish the research purpose, I collected data via survey and analyzed the obtained data with structural equation. The target population of this study was students in their 1st year of high school. Three hundred eighty three students were sampled from the target population with cluster sampling. The cluster factor employed in the sampling procedure was school type. The survey questionnaire measured research participants’ internal locus of control, mindset, and grit. The survey was conducted from the August 25th to the September 4th in 2015. After data cleaning, three hundred sixty samples were analyzed. The results of National Educational Assessment was used as a measure of participants’ academic achievement.
Locus of control was measured with Rotter’s scale (1966), mindset was measured with Dweck’s scale (1995), and grit was measured with a modified version of Grit-O scale (Duckworth & Quinn, 2007). I modified Grit-O scale through the exploratory factor analysis so that the scale be appropriate for my target population. Data were analyzed by utilizing the AMOS (v. 21.0) and the IBM SPSS Statistics (v. 23.0).
The results of this study were as follows: First, locus of control had a statistically significant effect on grit. That is, the higher the locus of control was, the higher the grit was. Second, mindset had a statistically significant effect on grit. That is, growth mindset affected grit in positive way. Third, grit had a statistically significant effect on academic achievement. That is, the higher the grit was, the higher the academic achievement level was. Fourth, grit was a full mediator factor that worked between locus of control and academic achievement. And finally, grit was a full mediator factor that worked between mindset and academic achievement.
Based on the finding of the study, major conclusions of this study were followed: First, corrected structural equation model which was modified according to the results of hypothetical model analysis was suitable to empirical analysis on research variables. Second, internal locus of control had direct effect on grit, and indirect effect on academic achievement. Third, mindset had direct effect on grit, and indirect effect on academic achievement. But no significant direct effect on academic achievement was found. Forth, grit had direct effect on academic achievement. Fifth, internal locus of control and mindset had significant indirect effects on academic achievement.
Based on the findings of this research, further research is suggested as follows: First, longitudinal studies that investigate the effect of grit on various achievements will shed more light on understanding the relationship between grit and long-term goal. Second, studies further validating and refining grit scales are needed so that we have better measure of grit. Third, this study limited factors related to grit only to a few factors derived from implicit theory. There are strong possibility that many other factors are related to grit. Thus, finding and investigating more factors related to grit will expand and deepen our understanding to grit. And finally, it would be desirable to devise measures that increase grit level and check their effectiveness so that we can take better advantage of the concept grit to improve the quality of training and education.

Key words: grit, mindset, locus of control, academic achievement