Study Habits

Contemporary Educational Psychology 30 (2005) 96–116 www.elsevier.com/locate/cedpsych

Why study time does not predict grade point average across college students: Implications of deliberate practice for academic performance
E. Ashby Plant*, K. Anders Ericsson, Len Hill, Kia Asberg
Department of Psychology, Florida State University, Tallahassee, FL 32306-1270, USA Available online 14 August 2004

Abstract The current work draws upon the theoretical framework of deliberate practice in order to clarify why the amount of study by college students is a poor predictor of academic performance. A model was proposed where performance in college, both cumulatively and for a current semester, was jointly determined by previous knowledge and skills as well as factors indicating quality (e.g., study environment) and quantity of study. The findings support the proposed model and indicate that the amount of study only emerged as a significant predictor of cumulative GPA when the quality of study and previously attained performance were taken into consideration. The findings are discussed in terms of the insights provided by applying the framework of deliberate practice to academic performance in a university setting. Ó 2004 Elsevier Inc. All rights reserved.
Keywords: Grade point average; Study time; Academic performance; Deliberate practice; Study habits

*

Corresponding author. Fax: [phone]. E-mail address: [e-mail] (E.A. Plant).

0361-476X/$ - see front matter Ó 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.cedpsych.2004.06.001

E.A. Plant et al. / Contemporary Educational Psychology 30 (2005) 96–116

97

1. Introduction The total amount of time that students report studying has often been examined as a potential predictor of success in school. It might seem that the more time that students spend studying, the better grades they should receive. Although students should increase their personal knowledge and skills by increasing the amount of time that they spend on relevant study activities, the relationship between the amount of study and achievement across students is less clear. Indeed researchers have consistently found a weak or unreliable relationship between the weekly amount of reported study time and grade point average (GPA) for college students (Allen, Lerner, & Hinrichsen, 1972; Beer & Beer, 1992; Gortner Lahmers & Zulauf, 2000; Hinrichsen, 1972; Michaels & Miethe, 1989; Schuman, Walsh, Olson, & Etheridge, 1985; Wagstaff & Mahmoudi, 1976).1 The most extensive study conducted on the issue, by Schuman et al. (1985) provides compelling evidence that ‘‘there is at best only a very small relationship between amount of studying and grades’’ (p. 945). In one of their studies, they found a weak, yet reliable relationship between reported study time and grades in the corresponding semester, but this relationship disappeared when studentsÕ SAT scores were statistically controlled. Schuman et al. (1985) argued that grades in college are primarily determined by aptitude measures, such as SAT, and attendance at lectures and classes. Subsequent investigators largely accepted the findings of Schuman et al. (1985) but questioned the generalizability of the findings across educational contexts (Michaels & Miethe, 1989) and student populations (Rau & Durand, 2000). In their study, Michaels and Miethe (1989) found a small (r = .18, p < .01) relationship between reported study and GPA, which remained after controlling for a number of background variables, such as high school rank, attendance, and reported study habits. They also found that studying ‘‘without listening to radio and television (no noise)’’ predicted higher GPA. Rau and Durand (2000) argued that Schuman et al.Õs (1985) findings were the result of their sample of undergraduates from the University of Michigan, which they posited are not representative of students in most large state universities. For example, they found that the students at University of Michigan reported studying an average of 25 h/week, whereas Illinois State University (ISU) students reported only 8 h/week (but see Schuman, 2001). Although Rau and Durand (2000) found that the amount of study was reliably related to GPA (r = .23, p < .001) for an ISU sample, the real benefits were only seen for students studying over 14 h/week (about 25% of the ISU students). Rau and Durand (2000) devised a variable of ‘‘academic ethic’’ to identify students who were committed to studying, which also predicted GPA, after controlling for high-school grades and scholastic aptitude (ACT) scores.

For the current literature review, we chose to focus on research that used official records of GPA as opposed to self-reported GPA and that used samples of regular college students and not pre-selected special populations.

1

98

E.A. Plant et al. / Contemporary Educational Psychology 30 (2005) 96–116

1.1. Deliberate practice and performance In trying to understand the small or unreliable relationship between study time and GPA, it may be helpful to consider the emerging literature on deliberate practice. Research into deliberate practice indicates that the amount of high quality practice accumulated during individualsÕ careers is closely related to their attained performance in a wide range of domains (e.g., Ericsson, 2002; Ericsson & Lehmann, 1996). Studies of the acquisition of expert performance have shown that extensive experience is necessary for individuals to attain high levels of reproducibly superior performance in the domain of expertise (Ericsson & Lehmann, 1996; Simon & Chase, 1973). However, all experiences are not equally helpful and there are qualitative differences between activities loosely referred to as ‘‘practice’’ in their ability to improve performance. There are clear limits on the benefits of experience. For example, many people know recreational golf and tennis players whose performance has not improved in spite of 20–30 years of active participation. The mere act of regularly engaging in an activity for years and even decades does not appear to lead to improvements in performance, once an acceptable level of performance has been attained (Ericsson, 2002). For example, if someone misses a backhand volley during a tennis game, there may be a long time before the same person gets another chance at that same type of shot. When the chance finally comes, they are not prepared and are likely to miss a similar shot again. In contrast, a tennis coach can give tennis players repeated opportunities to hit backhand volleys that are progressively more challenging and eventually integrated into representative match play. However, unlike recreational play, such deliberate practice requires high levels of concentration with few outside distractions and is not typically spontaneous but carefully scheduled (Ericsson, 1996, 2002). A tennis player who takes advantage of this instruction and then engages in particular practice activities recommended by the teacher for a couple of hours in deeply focused manner (deliberate practice), may improve specific aspects of his or her game more than he or she otherwise might experience after many years of recreational play. Ericsson, Krampe, and Tesch-Romer (1993) proposed that the acquisition of ex¨ pert performance was primarily the result of the cumulative effect of engagement in deliberate-practice activities where the explicit goal is to improve particular aspects of performance. These activities are typically designed by a teacher or by the elite performers themselves when they have reached a sufficiently high level of mastery. The specific goals of deliberate practice and the detailed nature of training activities will differ for a given person from practice session to practice session as it will from one person to another in a given domain and particularly across domains. However, the general goal of all forms of deliberate practice involves improving some aspect of performance in an effective manner and, thus, deliberate practice has a number of pre-requisites, including the capacity to sustain full concentration, a distraction-free environment, and access to necessary training resources. Hence to engage in deliberate practice the aspiring elite performers often need to travel to a training facility and to schedule the practice activity to assure the ability to sustain concentration during

E.A. Plant et al. / Contemporary Educational Psychology 30 (2005) 96–116

99

the daily practice activity (Ericsson, 1996, 2002, 2003a). Ericsson et al. (1993) and Ericsson (1996, 2002, 2003a) demonstrated that the attained level of an individualÕs performance is closely related to the reported amount of deliberate practice, primarily solitary practice focused on improvement, that he or she has accumulated since the introduction to a domain, such as chess (Charness, Krampe, & Mayr, 1996), sports (Ericsson, 2001, 2003a, 2003b; Helsen, Starkes, & Hodges, 1998; Starkes, Deakin, Allard, Hodges, & Hayes, 1996), and music (Ericsson et al., 1993; Krampe & Ericsson, 1996; Lehmann & Ericsson, 1996; Sloboda, 1996). In studies of college education, similar evidence has been accumulated for differential effectiveness of various learning activities. Inspired by Craik and TulvingÕs (1975) classic work on depth of processing, Schmeck and Grove (1979) found that college students with above average GPAs differed from students with below average grades in their reports of cognitive processes mediating their learning. The students with higher GPAs were found to endorse more inventory items about elaborative encoding and deep analysis and synthesis, but were not found to differ in their endorsement of traditional study and learning methods from the students with lower GPAs. In fact, they found that studentsÕ endorsement of traditional study was negatively related to their academic assessment tests (ACT). More recent research on effective learning (for reviews see Pintrich, 2000; Puustininen & Pulkkinen, 2001; Zimmerman, 2000) has explored successful studentsÕ reports of the regulation of learning activities and the study environment within educational settings. For example, Zimmerman and Bandura (1994) showed that self-efficacy (as rated by college students) and grade expectations predicted grades in a writing class. VanderStoep, Pintrich, and Fagerlin (1996) found that college students with low, medium, and high course grades differed in their reported learning characteristics for social and natural science but not humanities courses. Specifically, VanderStoep et al. (1996) showed that high achievers in social and natural science had more domain-specific knowledge, more adaptive motivational beliefs, and better self-regulation. More recently Zimmerman (1998, 2002) has developed a general framework for self-regulation in studying. He demonstrated close parallels between effective activities in studying in academic settings and self-regulated practice in the development of expert performance in many domains of expertise (Ericsson, 1996, 2002, 2003a, 2003b). The current paper seeks to identify observable indicators of effective learning activities in the complex domain of academic performance in a university setting by extending the theoretical frameworks of deliberate practice and self-regulated learning. We propose that distinctions between deliberate practice and other types of practice can be applied to studying and that this distinction can, at least in part, explain why measures combining all types of study activities in the school system are not valid predictors of grades. Furthermore, we propose a few observable indicators that would reveal active efforts by some of the students to plan study activities in environments that are conducive to deliberate practice and self-regulated study activities in college. Of particular interest are learning activities reflecting deliberate and self-regulated practice that are related to increased performance (GPA). However, in addition to factors that are hypothesized to promote the quality of study, there are numerous other factors in the college environment that also influence GPA

100

E.A. Plant et al. / Contemporary Educational Psychology 30 (2005) 96–116

and performance across a wide range of academic subjects (e.g., prior knowledge of subject, skills, and cognitive abilities). Therefore, our approach focuses on measuring a wide range of factors important for academic performance, so that we can statistically control for these factors and eventually estimate the relationship between study time and academic performance. 1.2. Toward a model of factors that determine grades during a semester in college Common measures of performance in college are the cumulated GPA or the GPA for a given semester. These measures are averages of course grades, which are likely determined by two types of factors. The first type can be measured prior to the start of a targeted semester, such as the knowledge, abilities, and skills that had been acquired prior to the start of the semester. The second group of factors consists of the concurrent study and the learning and non-learning activities that take place during the semester. We consider each of these types of factors in turn. 1.2.1. Factors reflecting conditions prior to the start of a semester Previously acquired knowledge, skills, and stable abilities relevant to a given course will directly affect performance on tests and the final examination. These factors will also have an indirect impact by influencing the amount and type of new learning that is necessary during the semester for a student to reach a given level of mastery. Based on a large body of research, the best measures of basic cognitive skills and abilities and prior learning are SAT scores, high-school GPA, and prior grades in college (e.g., Allen et al., 1972; Gortner Lahmers & Zulauf, 2000; Hinrichsen, 1972; Schuman et al., 1985). Allen et al. (1972), for example, found that high school rank was a better predictor of GPA than study time or test anxiety. Standardized assessments of aptitude such as SAT and ACT scores are also predictive of performance in college (Gortner Lahmers & Zulauf, 2000; Hinrichsen, 1972; Schuman et al., 1985). One might argue that the single best variable summarizing this information would be the cumulative GPA for college at the time of the start of the relevant semester. However, this measure also reflects many stable characteristics concerning quality and quantity of past study behaviors that are likely to be continued into the current semester. 1.2.2. Factors reflecting effective study during a semester If the goal is to predict GPA and cumulative GPA for students, it is necessary to focus on information that students are capable of reporting accurately from memory about the entire current semester. Although it would be fascinating if students were willing to report their detailed study processes for every hour of study during the semester, it would be virtually impossible to validate this information, particularly retrospectively. Consequently, we chose to focus on observable characteristics of activities that students actively initiated to influence not only the amount of study time but also the quality of study. Based on the deliberate-practice framework, effective learning requires high levels of concentration and focus on the study activities (Ericsson, 1996, 2002; Ericsson et al., 1993). As a result, studying should be more

E.A. Plant et al. / Contemporary Educational Psychology 30 (2005) 96–116

101

effective if it takes place in environments that allow full concentration (Zimmerman, 1998, 2002). Whereas some students may walk over to the library to study alone, others may study with friends and in settings with many potential distracters. However, studying is more likely to reach a quality consistent with deliberate practice and selfregulated academic learning if students schedule studying activities at suitable times and in locations where they would be unlikely to be interrupted and distracted. Consistent with this argument, when researchers have taken steps to assess distractions or interruptions to studying, they are typically successful in predicting academic performance. For example, Michaels and MietheÕs (1989) found that studying with the radio and TV was associated with a lower GPA. Hinrichsen (1972) found that the amount of effective study time (i.e., the number of uninterrupted minutes spent studying) predicted GPA. In addition, Allen et al. (1972) found that the number of interruptions that students reported during studying was negatively correlated with GPA. These findings suggest that students interested in excelling in school might be well served by choosing study environments with a low probability of distraction (e.g., studying alone in the library). We argue that such study environments are more likely to foster the kind of concentration and focus necessary for effective learning (i.e., deliberate practice and self-regulated learning). Based on research on expert musicians and other elite performers, we know that engagement in deliberate practice is not generally spontaneous but that future expert performers habitually practice at regularly scheduled times (Ericsson, 1996, 2002). The factors that control engagement in deliberate practice thus differ from the unplanned and spontaneous engagement in more enjoyable and effortless activities, such as leisure activities with friends (Ericsson et al., 1993). The need for sustained concentration, appropriate environment, and sufficiently long uninterrupted time intervals for deliberate practice requires long-term time budgeting and active prioritization. Therefore, given the competing demands for time in college, deliberate practice among college students would require active planning of their time. Similarly, self-regulated, effective learning is argued to require careful forethought and planning (Zimmerman, 1998, 2002). Consistent with these propositions, Britton and Tesser (1991) argued that because of the multiple demands on studentsÕ time, careful planning of time is critical to success. They believe that good organization and goal setting (i.e., planning activities a week or more in advance) created a more focused approach to studying and more efficient monitoring of goal accomplishment. Such focus and monitoring are critical to deliberate practice. Consistent with their theorizing, they found that self-management practices such as prioritizing tasks were predictive of college studentsÕ GPAs even when controlling for their SAT scores (also see Gortner Lahmers & Zulauf, 2000). In order for students to engage in the high quality of study necessary for deliberate practice, it is also important that students expend the effort to come to the classes and attend a large percentage of them. It is in the classroom where students receive instruction regarding what information and skills need to be studied and practiced for high levels of performance. Therefore, it is expected that a high level of attendance is required for optimal quality of studying. In addition, other demands or draws for studentsÕ time tend to influence the use of available time and, likely, energy

102

E.A. Plant et al. / Contemporary Educational Psychology 30 (2005) 96–116

for studying. For example, students who work for pay for a large number of hours each week will have fewer hours available for studying and less freedom to choose when to study. As a result, instead of selecting study time based on motivation and level of energy, people working many hours for pay may be left with fewer options for when to study (e.g., late at night, between classes), which may lead to less effective and less focused studying. Similarly, students who choose to spend extensive time partying may also limit the available time for studying as well as the quality of their study time. 1.3. The current study The current study examines those factors likely to indicate the high quality of study among college students, endemic to deliberate practice and self-regulated learning, in hopes that it will help to clarify the relationship between study time and GPA. Specifically, the current study examined a range of factors reflecting conditions prior to the current academic semester (i.e., high-school GPA, SAT scores) as well as factors from the current semester (i.e., study time, study environment, and planning) and attempted to predict college performance both cumulatively and for a current semester. First, we assessed the relationship between estimated study time and cumulative GPA. We then controlled for previous performance in high school, college, and on standardized aptitude tests before examining the effects of factors from the current semester, including those related to quality of study on college GPA. Once previously acquired knowledge, skills, and abilities are statistically controlled, we predict that factors related to quality and quantity of study would emerge as predictors of college GPA. Therefore, in the current study, participants were asked about a range of their activities in order to gain a detailed picture of the characteristics as well as quantity of their study behavior. Across the factors assessed in the current study, we focused on objective and verifiable information, such as official university records (e.g., GPA, SAT scores). We selected quantifiable assessments that are verifiable in principle and minimally subjective. For example, the time spent studying in the library, attendance to classes, participation in parties, and outside employment can be validated in future studies by direct observation and interviews of close friends and roommates. We also collected information about studying and other activities in diaries. Similar methods have been used to validate concurrent and retˆ ´ rospective estimates of deliberate practice (Cote, Ericsson, & Beamer, 2004; Ericsson et al., 1993; Krampe & Ericsson, 1996). By examining a large range of factors simultaneously, the current work allows us to identify those factors that provide an independent contribution to grade point average. We anticipated that students, who reported studying behaviors that reflect important aspects of deliberate practice (i.e., focused, uninterrupted, and carefully planned) (Ericsson, 1996, 2002, 2003a; Ericsson et al., 1993) and characteristics theoretically related to self-regulated learning (Zimmerman, 1998, 2002), would excel. Specifically, based on the findings regarding deliberate practice and the review of the literature on academic performance and self-regulated learning, we anticipated

E.A. Plant et al. / Contemporary Educational Psychology 30 (2005) 96–116

103

that students who studied in a quiet environment with fewer distractions and who carefully organized their study time would achieve higher performance. Further, we expected that students who attended a large percentage of classes and had fewer outside competing demands for their time and energy, such as working for pay or frequently attending parties, would have higher GPAs.2 Finally, when other factors that may influence the quality of study time (e.g., study environment, planning) are taken into account, we predicted that the amount of reported study time would emerge as a predictor of academic performance.

2. Method 2.1. Participants Participants were 88 volunteer, undergraduate college students (49% male) from Florida State University in Tallahassee, Florida. Participants were required to have completed at least 1 year or 24 credit hours at the university (mean credit hours = 58.52, SD = 27.39) to insure that there were enough credit hours to produce a meaningful GPA. Participants were drawn from classes in the departments of Psychology and Education as well as from sports teams at the university. The mean age of the participants was 19.82 years (SD = 1.19). All participants signed informed consent documents and release forms for their official university records. 2.2. Procedure Participation took place in group sessions (typically 15–20 students) in classrooms at the university. Participants were given a packet of materials including a Time Allocation and Academic Performance questionnaire, seven time log forms, and seven stamped and addressed envelopes. Participants were given an overall explanation of the study and the procedure to be followed for completing the time logs. Participants then completed the questionnaire, which took approximately 45 min. Participants were asked to complete the time logs on a day-to-day basis over the next week and mail the completed forms to the investigators daily. Most participants followed the instructions for remitting the completed forms, but some participants returned multiple completed forms at the same time. The overall purpose of the procedure was to maintain an awareness of their daily activities so that they could be accurately reported.

2 Although these measures capture objective characteristics that make deliberate practice more likely, they do not directly measure the quality of study. We chose to focus on observable, objective behaviors that we believe to be associated with high quality deliberate practice as opposed to more direct assessments of self-reported quality of study in order to avoid potential subjective biases in the direct quality ratings.

104

E.A. Plant et al. / Contemporary Educational Psychology 30 (2005) 96–116

2.3. Materials 2.3.1. Official university records The University official records were used to acquire information regarding the participantsÕ grade point averages from high school and college level courses accepted by the university prior to the current semester on a four-point scale (e.g., A = 4.0). In addition, participantsÕ SAT/ACT scores were collected. To create a single standardized test score, students ACT scores were transformed into SAT scores using the UniversityÕs equivalency formula. In addition, the GPA for the fall semester during which the study was conducted was obtained from the official university records after the end of the semester. 2.3.2. Time allocation and academic performance questionnaire The questionnaire packet was designed to elicit information from the participants regarding their academic performance at the university and the factors that may influence their academic performance. The questionnaire assessed background information, academic history, university academic performance, time allocation, and study methodologies. From the major categories listed above, questions bearing directly on the current investigation were selected for analysis. Participants reported the percentage of basic core classes (i.e., English, mathematics, and major courses) that they had attended. They were also asked to report the percentage of their most difficult class and their second most difficult class that they attended. These percentages were averaged to create the class attendance variable (a = .73). The time allocation section asked participants to report the number of hours a week they spent in a variety of activities. Relevant for the current investigation, participants were asked to report the number of hours a week they spent working for pay (hours of work) as well as the number of hours a week they spent at parties or clubs (hours partying). In addition, planning practices were obtained by examining how participants reported that they most often planned their time. Participants selected their method of planning from a list that included a computer planning program, a commercial planner, a calendar, a daily to-do list, and keeping it in their head. These responses were coded to create a planning variable. Participants who reported that they used long-term planning that included some advanced planning (e.g., a computer program, commercial planner, or calendar) were coded as having long-term planning (53%). If they used a daily list or kept their plan in their head, they were coded as not using long-term planning (47%). The study methodologies section asked participants about their study habits including how much they studied, where they studied, and whether they studied alone. Participants reported the average number of hours they studied per week for their courses using two different approaches. First, they were asked to report the number of hours per week they studied for each of their classes. They were next asked the number of hours per week that they studied in a variety of locations (e.g., a home, library, etc.). The total number of hours that they reported studying across each of these measures was summed. These two measures of study time were strongly

E.A. Plant et al. / Contemporary Educational Psychology 30 (2005) 96–116

105

correlated with each other (r = .71), and, therefore, the two totals were averaged to create a single measure of total study time. To determine whether participants typically studied in a quiet, solitary environment, we examined the percentage of the time that they reported studying at the library versus at home and the percentage of time that they reported studying alone versus with other people present. Based on the concept of deliberate practice people should study most effectively if they study alone in a quiet environment with few distractions. Therefore, the two percentages were summed to create an index of the degree to which they typically studied in a quiet environment with few distractions (study environment) with higher numbers indicating a better environment. 2.3.3. Daily time logs After completing the questionnaire, participants were requested to complete a daily time log for seven consecutive days. Space was provided to note the participantÕs activities (e.g., studying, sleeping, hanging out with friends) in 15-min segments throughout a 24-h day. Participants were instructed to note ‘‘Personal’’ in the time slots for those activities that they felt uncomfortable reporting. In addition, participants reported whether the week covered by the daily time logs was a typical or atypical week (for either academic or non-academic reasons). The number of hours that participants reported studying across the daily time logs was tallied as an additional assessment of study time. Unfortunately, the time logs were only completed by 60% of the participants and could not be universally compared to the questionnaire data.

3. Results As a first step in understanding the factors that influence performance in college, we examined the zero-order correlations between the different assessments of college GPA (i.e., cumulative, fall semester) and the variables that we anticipated would predict college GPA. The full set of correlations between the measures can be found in Table 1. In general, the relationships between the different assessments of GPA and the predictors were quite similar across the measures of GPA. Whereas neither of the assessments of GPA was associated with the amount of time students studied, they were both positively associated with high-school GPA (and SAT scores for cumulative GPA). In addition, consistent with expectations, attending classes and having an organized approach to planning were associated with a higher cumulative GPA. Attending classes was also associated with a higher fall semester GPA. For fall semester GPA, studying in a quiet environment was related to a higher GPA. Further, across the assessments of GPA, working long hours at a job and spending more hours partying or at clubs were associated with a lower GPA. It is also worth noting that the amount of time that students spent studying was negatively related to their SAT scores. This finding is consistent with the idea that students who have superior prior knowledge and skills coming into the college could

106

E.A. Plant et al. / Contemporary Educational Psychology 30 (2005) 96–116

Table 1 Intercorrelations between measures 2 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. GPA fall 2000 Cumulative GPA Study time High-school GPA SAT scores Attendance Planning Study environment Hours of work Hours partying .55 —
*

3 .02 .11 —

4 .25 .33* À.05 —
*

5 .17 .24* À.26* .39* —

6 .27 .28* .04 .13 À.07 —
*

7 .17 .26* .20 .01 .01 .12 —

8 .27 .17 À.21* À.01 À.11 .03 À.01 —
*

9 À.24 À.30* .14 À.17 À.05 À.06 .10 À.05 —
*

10 À.22* À.28* .11 À.19 À.10 À.31* .06 À.03 À.03 —

Note. N ranges from 83 to 88 depending on missing data. * p < .05.

attain a given GPA with less study time than those with weaker prior knowledge and skills. Also, students who studied in a quiet environment with few distractions tended to study for less time than those who studied in a less ideal environment. Not surprisingly, students who spent more hours at parties and clubs tended to attend a smaller percentage of their classes. Finally, high-school GPA and SAT were reliably correlated. 3.1. Examination of cumulative GPA Having established that the zero-order correlations were consistent with predictions, we were interested in examining which of the potential predictors were independently associated with college GPA. To this end, a hierarchical regression analysis was conducted on participantsÕ measures of GPA. As the more general measure of GPA, we first examined cumulative GPA up to the fall semester during which we collected the participantsÕ responses to the questionnaire. In the first step of the regression, the average study time per week based on the questionnaire responses was entered into the equation to determine the impact of study time in the absence of the other potential predictors. Next, high-school GPA and SAT scores were entered into the regression as indicators of prior knowledge and skills. For the third step, other variables that were anticipated to influence academic performance (i.e., taking advantage of instruction and study quality) were entered. These variables included class attendance, planning, study environment, and hours of work per week. For the final step of the regression, high-school GPA and SAT scores were removed from the equation. This step allowed us to identify both the variance independently accounted for by prior knowledge and skills and the effect of the other predictors when the variance due to these variables was not removed from cumulative GPA. The findings from the analyses can be found in Table 2. The results from the first step of the regression indicated that study time alone was not a significant predictor of cumulative GPA, F(1, 81) = 1.01, p = .32 (b = .11). When high-school GPA and

E.A. Plant et al. / Contemporary Educational Psychology 30 (2005) 96–116 Table 2 Hierarchical regression analyses across measures of GPA Cumulative GPA R2 Step 1: Total Model R Study time
2

107

Fall GPA

Fall GPA controlling for cumulative GPA b