THE SELECTIVE VALUE OF POWERS' GENERAL CHEMICAL TEST, SCALE "A" LAWFSN~~ EDWARDSTOUT,MIAMI UNlYERslTY, OmoRD, OHIO This paper reports the first of a series of studies made by the author on the use of chemical scales to determine a student's fitness for carrying college chemistry based upon one year of high-school preparation in the subject. The results herein indicate that: The correlation between Powers' Scale "A" scores and student averages decreased as the period of stndy increased. A rather good correlation was obtained between the Powers' Scale "A" and academic marks for the very poor and the very good students, according to quintette placements. Very little relation was noted between the ability of a student and his test score, unless other factors were taken into consideration. For some time the author has been interested in some scheme whereby he might be able to measure rapidly the ability of a student to carry on work in a college course in chemistry based upon one year of high-school preparation. Last year it was decided to measure the attainment of students as measured by Powers' General Chemistry Test, Scale "A," and then to follow very carefully the college life of the students throughout the college year so as to learn as much as possible concerning the various disturbing extra-curricular elements which apparently caused variation from the academic result that might have been accomplished. Discoumting for these variables, it was hoped to see what relation existed between attainment at that period and ability to pursue the course. Experimental Procedure At the first class period in the Fall the Powers' Scale "A" was given in due form, and the tests scored. No attempt was made to classify or section according to ability, as it was the purpose of this study to have aU conditions the same, or as nearly the same as possible, throughout the experiment. All students had the same instructor during the year, and no attempt to correlate these data was made until the close of the spring semester, so as to leave the instructor unbiased in his opinion of the student and his work. As there were sixty-five cases under observation it seemed logical to arrange the grades in groups of five, for purposes of comparison and so, instead of having the customary decile placements, we had what might be called quintette placements. As a number of the students failed in the first semester's work and some others had to drop out during the second semester for other reasons, the Powers' scores had to be listed according
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POWERS' GENERAL C H & ~ C ATEST, I . SCALE "A"
1139
DATA AND RESULTS
01the sixty-fivestudents under observation the following data were obtained: Student No.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 2'3 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
Academic mark at 12 weeks 18 weeks
36 weeks
62
.. .. ..
52
48 60 63 64 56 72 53 69
... .. ..
70 58 58 78
.. ..
58 58
..
60 52
..
44 60
.. ..
69 64 53 69 68 71 62 58 68 68 92
..
64 43 62
DATAAND RESULTS (Concluded) Studmt
No.
48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
Powers'
reme
6 weeks
33 34 34 34 35 35 35 35 36 37 38 38 40 42 43 44 46 49
90 60 80 94 60 82 74 90 85 74 71 90 70 73 81 90 86 86
Academic mark at 12 weeks 18 weeks
90 58 80 90 61 70 81 92 90 83 69 91 68 75 85 85 92 77
36 neeks
90 55 71 90 60 61 80 92 90 82 67 95 73 70 89 85 93 61
72
.. 68 78 58 61 74 95 91 89 61 81 59 68 81 76 89 58
to both the eighteen weeks and the thirty-six weeks class rolls. Students were placed according to the Powers' ranking and this placement compared with a similar placement according to the six, twelve, eighteen, and thirtysix weeks averages. The following table of results was obtained: STUDENT RANKING ACCORDING M QUINTETTE PLAC~ENIS .. Sttldent NO.
Powers' "A" "18"
6 weeks
Academic standing at 18 weeks
12 week.
Powers' "A 36 weekn
"36"
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POWERS' GENERAL CHEMICAI. TEST,SCALE"A"
S ~ E NRANKING T ACCORDINO To QUINTETTE PLACEMENTS P O T , ' 18"
"A"
6 weeks
Academic standing at 12 weeks 18 weekr
1141 (Concluded)
36 weeks
Powern' "A" "36"
.. 8
8
..
8 8
..
8
8
.. .. 7
7 7 7
7 7 5 5
5 5
5
.. 4 4
4 4
.. 4
4
3
3 3 3 2 2 2
2 2 1 1 1 1 1
Discussion of Results Nine students showed a perfect correlation between the Powers' placement ranking and the eighteen weeks placement ranking. These cases
were numbers 2, 4, 5, 6, 8, 24, 45, 54, and 64. Ten students showed a perfect correlation between the Powers' placement ranking and the thirtysix weeks placement ranking. They were numbers 6, 10, 18, 19, 26, 30, 41,42, 54, and 64. Therefore, for the year, based on the two semester averages, only three cases showed a perfect correlation, numbers 6, 54, and 64. It seems worthy of note that only the very good and the very poor students show consistent placement througho~tthe year. It is evident that these classes are damaged less by the extra-curricular activities than the other grades of students. The first class has sufficient ability and interest to insure their spending the necessary time on their work. The second class is hopeless anyway. Of the thirteenth quintette, according to the Powers' placement, only two students passed the work of the first semester and only one passed that of the second semester. This one student, case ndmber 1, employed a special tutor for the last thirty weeks of the academic year. This possibly accounted for his passing the course. It would seem wise, therefore, to eliminate this group a t the start, unless special instructional facilities were available. In an attempt to explain the poor correlation existing between the remainder of the cases and the Powers' placement, observations were made on all students to try to discover contributing causes. The following factors were deemed necessary to take into consideration in the interpretation of the accuracy of the results. 1. Lazy Students: numbers 21, 22, 24, 25, 32, 35, 39, 40, 44, 46, 27, 29, 58, 61, and 65. Their failure to spend the necessary time in preparation most certainly cansed a lowering of rank almost directly proportional to the intensity of the malady. 2. Students enrolled in the first half of the course for the second time: numbers 26, 28, and 60. Their Powers' placement rank naturally gave abnormal results, because their longer period of preparation introduced a new factor. 3. Students who had allowed one or more years to elapse between their high-school and college courses: numbers 10, 11, 13, and 53. Two of these people did better than might have been predicted while the other two sxffereda second complication, mentioned below. 4. The work of three students was handicapped by outside activities: numbers 10, 34, and 53. 5. Number 31 started in late, accounting for his lower ranking in academic marks. 6. This leaves a t least one other large factor unaccounted for, namely, the character of the work in the high schools themselves. Numbers 4, 8, 9, 10, 14, 17, 20, 33, 37, 43, 48, and 51 all came from poorly equipped schools and did better work than their rating would normally lead one to
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POWERS' GENEUL CAEMICN.-ST.
SCALE "A"
1143
expect. On the other hand, from similarly equipped schools numbers 7, 23, 29, 30, 50, and 53 did poorer work. Again, numbers 36,38, and 55 came from well-equipped schools and did better work than predicted, while numbers 12, 15, 27, 40, 52, 58, and 65 from similar or better schools did much poorer work than their ranking predicted. I n general, however, it seemed that more injustice was done the students that came from poorly equipped schools by such a method of classification than from any other cause. Yet, none of these students were so poorly trained that they failed to get enough of a grasp of the subject t o enable them to keep out of the lowest placement group. If one were t o discount for all these factors mentioned in the first six or rather five and a half classes above, a rather high per cent correlation would seem to exist. The previous method of observing the correlations dealt only with individual cases. I n an attempt to arrive a t general correlations between Powers' Scale "A" scores and the six, twelve, eighteen, and thirty-six weeks averages, correlations were calculated according t o Pearson's formula
The following values for "r" were obtained: Sixweeks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.661 Twelve weeks.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.527 Eighteen weeks.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.504 Thirty-six weeks.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
0.491
These figures showed that the highest general correlation existed a t the six-weeks period and that this per cent progressively decreased as the period of study increased. Now, if this test measured the true ability of a student to handle a course in college chemistry based upon a year of highschool chemistry, these correlation values "r" should become progressively higher as the period of study increased. Conclusions 1. The Powers' Scale "A" is somewhat of a measure of a student's attainment a t the beginning of the course. 2. The lowest quintette placement has little chance of satisfactorily passing the work in college chemistry, and the higher groups have a splendid chance, provided other factors do not become paramount. 3. The Powers' placement does a rank injustice t o students who work hard, have good ability, but poor preliminary training 4. Assuming that all extra-curricular factors could he eliminated and that all preliminary training was equally good or equally poor, it is believed that the Powers' placement could be effectively used to measure the ability of the student in this field.
