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Research and Education Reports |
| ABSTRACT |
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Key Words: case-based teaching problem-based teaching lecture-based teaching comparison
| INTRODUCTION |
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Since the incorporation of PBL, several studies have attempted to evaluate its effectiveness. One study observed no differences in student test scores between small-group PBL students and lecture-based (LB) veterinary students in a third-year neurosurgery course.4 LB students were exposed to more content than students in the PBL group, where the emphasis was on problem solving. Although PBL students tended to perform better than LB students on immediate and one-month post-material tests, the PBL students also tended to have lower satisfaction with their learning. Significantly more LB students agreed with the statements "good learning experience" and "learned a large amount of facts." Students in the PBL group were exposed to ill-defined real-life problems, whereas LB students were given more clear-cut information, and the authors suggest that PBL students may have been unfamiliar with the method and thus became somewhat frustrated with making judgments rather than having definitive answers.4 Other studies of small-group PBL have used student and faculty feedback and surveys to assess its effectiveness.5–9 In general, small-group PBL teaching/learning is well received by both faculty and students, although there are repeated concerns about lack of student time, lack of course time, and class size.5–9
A potential solution to the time concerns associated with small-group PBL is to use a blended cased-base/problem-based approach (CB/PB) in large groups, a methodology described for courses in veterinary clinical pathology and urinary-system physiology.10,11 In both instances, active learning with student participation in case discussions was well received by students, but examination performance was not directly compared between the CB/PB and LB methods. The purpose of the present study was to compare examination performance between third-year veterinary students taught in a large-group CB/PB setting and those taught in a large-group LB setting.
| MATERIALS AND METHODS |
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Teaching Methods
The first group (CB/PB) was taught using a large-group CB/PB method and addressed the following problems: (1) azotemia, (2) polydipsia/polyuria, (3) proteinuria, (4) pollakiuria-dysuria-stranguria, hematuria, and (5) urine retention and urine leakage (see Table 1). The introduction to this portion of the course syllabus stated,
The format for this course is primarily problem-based learning by way of large group case discussions. Most of the class time will be devoted to discussion of clinical cases. The emphasis in these discussions will be on: 1) identification of patient problems, 2) developing differential diagnoses for these problems, 3) what approach should be taken to establish the definitive diagnosis, and 4) how to manage the problem. No formal lectures are planned for this portion of the course. In order to gain more from the case discussions, it is recommended that you study the cases ahead of time. Getting together in small groups outside of class to work on the cases is also recommended. Case discussions during class time will be improved by your input.
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Table 1: Cases covered by the CB/PB group and topics covered by the LB group
A short introduction to each problem was provided by the instructor, and a case discussion followed. Case discussions consisted of providing history; physical examination findings; and CBC, serum biochemistry, and urinalysis results and asking the students to sequentially develop (1) a problem list, (2) a list of differential diagnoses for each problem, (3) a hypothesis diagnosis based on intersecting differential diagnoses, and (4) a list of additional diagnostic tests or treatments to prove or disprove the hypothesis. After this stepwise discussion, the case was summarized and additional questions were posed by the instructor as necessary to ensure complete coverage of the problem as well as of the pathophysiology and other learning objectives underlying the case presentation.
The second group (LB) was taught using lectures addressing various urinary topics (see Table 1). The introduction to this portion of the course syllabus stated,
This course is designed to teach the etiology, pathophysiology, clinical signs, diagnosis, differential diagnosis, and treatment of disease conditions that affect the urinary system of dogs and cats.
Material in this section was presented to students as outlined in most medical textbooks.
The CB/PB and LB groups were taught simultaneously in separate classrooms to prevent students from attending both classes. The two course instructors rotated, so that both groups had exposure to their individual teaching styles. The teaching assignments were allocated by randomly assigning one instructor to the first class period in each group, then alternating the assignments. The instructors met each day after class to ensure that there were no discrepancies in the information provided and to ensure continuity in the case presentations. The materials distributed to the two groups were different, but the overall subject material and content were similar. Any student could access either set of materials via the college intranet, and the learning objectives provided for each topic (LB) or problem (CB/PB) were the same. Access to both sets of notes and identical learning objectives were considered necessary to gain students acceptance and participation.
Evaluation Methods
Two multiple-choice examinations were developed with input from the Office of Educational Innovation and Evaluation (OEIE) at Kansas State University. Both examinations contained the same number of questions of lower (knowledge/factual), medium (knowledge with application), and higher (application and analysis) cognitive difficulty (see Appendix 1). The difficulty level of each question was determined by OEIE faculty based on Bloom's taxonomy,12,13 which addresses cognitive domains emphasizing the attainment, retention, and development of knowledge based on a hierarchy of six categories, from less to more complex. All students took the same examination at the end of the course. Performance on this examination determined their grade. Four months later, a different examination was given; student participation in this second examination was voluntary, but a monetary incentive was offered.
Faculty at OEIE designed different student feedback forms for the two groups. There were 23 common questions and two questions specific to each group (see Appendix 2). Two sections on the form used five-point Likert scales ranging from "strongly disagree" to "strongly agree"; the other sections contained multiple-choice or short-answer items.
Statistical Analysis
Categorizing the class into two groups of 55 students provided 80% power to detect a method effect of approximately 7% difference in mean test score. The question difficulty category–specific score for each student was calculated by dividing the number of correct responses by the number of questions in the specific question difficulty category. The question difficulty category–specific score was used as the outcome for an analysis of variance (ANOVA) for each examination. A full model was developed for each examination controlling for the effect of individual student, group, question difficulty category, and the interaction of group by question difficulty category. For analysis of differences between the two examinations, the difference between scores in each question difficulty category was calculated for each student. A within-subject ANOVA was performed on the question difficulty category–specific differences, including group and the interaction of group by question difficulty category. Overall error rate was controlled for post-hoc hypothesis testing by applying the Bonferroni correction to adjust critical p-values. The critical p-value used for the three comparisons was p < 0.017.
In order to compare the results of the CB/PB group and the LB group, mean scores were computed for the self-assessment items on the student feedback form (Questions 1–12). For comparison of the overall results between groups, a Welch t-test was used. This analysis was conducted because statistically significant differences were found in variance and standard deviations between the groups. For the open-ended questions, student responses were coded and analyzed to identify themes, both in the aggregate and by group.
| RESULTS |
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| DISCUSSION |
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The stated objectives were partially achieved in the present study. Compared with LB students, the CB/PB students scored significantly higher on the application and analysis questions on the first examination and had a higher self-assessment of their problem-solving skills. In addition, a higher percentage of the CB/PB students accessed online material. Although differences in examination scores have been difficult to identify, outcomes assessment of PBL in medical school curricula has demonstrated improved scores on licensing examinations and improved performance in clinical rotations.20,21
Overall scores on both examinations were lower than expected, but the examinations developed for the study were intentionally made difficult, in an attempt to identify differences between groups. The instructors expected LB students to perform better on the first examination, especially on the lower- and medium-difficulty questions, and CB/PB students to perform better on the second examination, especially on the higher-difficulty questions, but the results of the two groups were similar. Students gain acceptance into veterinary school largely by excelling in LB educational systems; thus, it might be anticipated that a subset of this group taught using CB/PB would not outperform another subset. In addition, it was common for the CB/PB students, at least initially, to feel stressed about the new teaching strategies and whether they might be misdirected or inefficient.
The CB/PB students spent more time online accessing LB materials than LB students spent accessing CB/PB materials, perhaps because the CB/LB students were concerned about missing factual material or because they lacked experience with the CB/PB format. The LB students reported a greater level of comfort with their course expectations than the CB/PB students did; conversely, the CB/PB students reported an increased ability to solve real-world problems, and on the first examination the CB/PB students outperformed the LB students on the higher-difficulty questions.
Scores on the lower- and medium-difficulty questions decreased between the first examination and the second. Both groups improved their scores on the higher-difficulty questions, and scores increased to a greater extent in the LB group than the CB/PB group. This result may be due to the subsequent exposure of both groups to CB/PB teaching in later sections of the parent course and in other courses.
This study has several limitations. First, the study period was short (14 class periods). Second, neither the CB/PB group nor the LB group used one model exclusively: case examples were presented to the LB group, without discussion, and brief topic reviews were presented in the CB/PB group. The latter was considered necessary based on a previous study in which 96% of students stated that the PBL format would be improved by a brief introduction to the topic prior to discussion of the material.11 Third, the level of student/faculty and student/student interaction associated with the CB/PB method would likely have been different if the entire class of 110 had been involved; in this study, the LB students met in their regular large classroom, while the CB/PB students met in a smaller room that may have facilitated the discussion process. Finally, contamination across groups occurred, because students communicated across groups and all students could access all materials. Although this cross-fertilization likely enhanced the learning experience for both groups, it also probably made detecting differences in performance between groups more difficult.
Problem-based learning has been defined in many ways. Traditional PBL involves small groups of students meeting with a facilitator who helps guide them through a problem or case. The methodology described in the present study may be best described as large-group case-based discussions facilitated by an instructor. Two of the major concerns raised about PBL concern the amount of faculty time it requires and its efficiency in disseminating large amounts of material within relatively short time frames. The results of this CB/PB teaching study may partially alleviate these concerns.
| APPENDIX 1: SAMPLE EXAMINATION QUESTIONS |
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Which one of the following drugs affects urinary bladder (detrusor) tone?
Higher-Level Questions
A 9-year-old spayed female domestic shorthair cat is presented for evaluation of polyuria/polydipsia (PU/PD). Physical examination reveals slightly dry mucous membranes and decreased muscle mass (body condition 2/5). The cat struggles a bit during collection of blood and urine. Results of minimum data base are shown below.
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Based on the information you have, which one of the following is the most likely mechanism for PU/PD in this cat?
Of the following diagnostic tests, which should be performed next in this cat to better define the cause of the PU/PD?
| APPENDIX 2: STUDENT FEEDBACK FORM, CB/PB GROUP |
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Student Feedback Form: Case-Based/Problem-Based Section
The purpose of this questionnaire is to collect your feedback about the Urinary Section of Medicine II. We are interested in your perspective of how the class was structured, and any suggestions you may have on how future classes could be improved. The information you give will be entirely confidential; all of the responses will be collected and analyzed by the Office of Educational Innovation and Evaluation on campus. The aggregate responses will be reported back only after the section is completed and grades have been assigned. If you have any questions about this process, please feel free to ask Dr. Grauer or Dr. Forrester for more information. Please take a few minutes to complete the entire form.
Please answer questions 1–12 using the following scale:
(Please circle your response Yes or No for questions 13–16)
Please answer the following questions:
Please complete all the items by circling the number that corresponds with your view for each instructor using the SD, D, NA/D, A, or SA scale.
Thank you for taking time to complete this form.
| ACKNOWLEDGMENTS |
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| Footnotes |
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Gregory F. Grauer, DVM, MS, is a Professor in the Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, 1800 Denison Ave., Manhattan, KS 66506 USA. E-mail: ggrauer{at}vet.ksu.edu.
S. Dru Forrester, DVM, MS, is a Scientific Spokesperson for Hill's Pet Nutrition, Inc., 400 SW 8th Ave., Topeka, KS 66603 USA.
Cindy Shuman, PhD, is an Evaluator in the Office of Educational Evaluation and Innovation, College of Education, Kansas State University, 2323 Anderson Ave., Manhattan, KS 66506 USA.
Michael W Sanderson, DVM, MS, is an Associate Professor in the Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, 1800 Denison Ave., Manhattan, KS 66506 USA.
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