SOME FUNDAMENTALS OF DESIGNING TABLES OF DATA' ETHALINE CORTELYOU A m o u r Research Foundation, Chicago, Illinois
IN
EXCHANGING shop talk with other report editors, I am always amused a t the wide variety of tasks management sees fit to assign to the report editor; the job seems t o be the catch-all for any unassigned duties. Yet I am sure that teaching has not been recognized as one of the basic duties of good technical editing. A writer should he able t o learn something from the editing of his report, so that his next report will be better. If a writer's sixth report requires the same kind and amount of editing as his first, something is radically wrong. The blame probably can be placed upon unreasonable editorial requirements or upon poor authoreditor relations. Since poor spelliag and grammar are the most common and most obvious weaknesses of technical writers, I suppose each of us has his own subtle methods of teaching these subjects to his writers. But what do you do about t,eaching your men to report data intelligently? Since space is limited, I shall discuss only one phase of the problem, the design of tahles of data. I am sure that on the problems of spelling and grammar all of us have been tempted to give up and just correct the mistakes without trying to improve our writers. But we cannot do that with tables of data because the scientist who collects the data is best equipped t o interpret and evaluate them, and the design of a good tahle is dependent upon interpretation and evaluation. So I have assembled a few fundamentals of tabulation which I have found useful in helping others design tables for the presentation of their data. These fundamentals can best be explained by examples, so I have "faked" some tables to illustrate my points. To borrow a technique from advertising, we might label almost all the A tables "Before" and the B ones, "After." (1) If four or more items of data are given, they should be presented in tabular fawn. In Example 1 notice horn much easier it is to understand the table. (2) Every table should have both a number and a title. The title should be brief, hut it should clearly identify the information contained. with reference t,o t,he t,ext,. ~~-~~ If you follow the practice of listing table titles in the Table of Contents, your authors will realize that they cannot have a long list of identical titles but must individualize each. (3) Even qualitative comparisons and contrasts are more easily understood in table form. ~
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' Presented at a round table discussion on Problems of Technical Editing sponsored by the American Documentation Inst,itute, Washington, D. C., Nov. 6, 1953.
I n Example 2, as in Example 1, reporting the data in a tahle is an aid to understanding. Incidentally, it is important that your writers realize that not all data are numerical. (4) Columns and rows must have identifying headings. (5) Units of measurement must be given. Usually, the column or row headings are the logical locations for units. Lack of such identification seems to be the most common failing of tables. (6) The same unit of measurement should be used ,for comparable properties or dimensions. EXAMPLE 1
The daily low-X diet, called Diet A, was prepared by adding t o 10 g. of skim milk the equivalents of 0.0003 g. of iron from FeSO4.7H2O,0.0001 g. of zinc from Zn(GHaOn)z, 0.0001 g. of copper from C U S O ~ ~ H ~ O , 0.0026 mg. of iodine from KI, and 0.0008 g. of manganese from MnS04.H20. TABLE 1
Low-XControl Diet. Diet A Mineral
.h'g./lO
g.
skim milk
Source
EXAMPLE 2
Streaked animals, ss, ran be produced only by the following matings: (a) streaked ss X streaked ss, (b) heterozygous Ss X streaked ss, (c) heterozygous Ss X heterozygous Ss. In mating ( a ) all offspring will be streaked; in mating (b) in which one of the parents mas streaked ss and the other heterozygous Ss, half of the offspring will be streaked; in mating (c) in which both parents are heterozygous, one-fourth of the offspring will be streaked. TABLE 2 Matings Resuired to Produce Stmaked Animals. ss
Slreaked Pa~enls Streaked ss X streaked ss Heterozygous Ss ss H~~~~~~~~~~~ss streaked heteroZvgous Ss
offspring, ss
AU
'1s '/a
NOVEMBER, 1954
591
Note: fly ash type A, untreated; fly ash type B, Aerotec separated.
Notice in Tahle 1 of Example 1 that all the weights are converted to milligrams. ( 7 ) The units of measurement used in a table should all be of the same system, such as metric, English, or apothecary. Of course, your engineers will insist that their convention demands a mixture. You may need to ask them to cite examples from printed literature to justify their usage. (8) If an item is repeated several times i n a table, probably it should appear just once i n the title, in a footnote, or in a column w row head. Often such repetition obscures important similarities, as you can see by inspection of the two tables in Example 3. The third and seventh columns of Table 3A have been eliminated in Table 3B by inserting the information in the title. The fourth, fifth, and eleventh columns of Table 3A have been eliminated in Table 3B, and the use of the information in inserts serves to group related data. See Example 4, also. (9) Column and row headings should be used to group related data. See t h e B tables of Examples 3 and 1.
Sample 1, flat surface; 2, curved surface.
TABLE 3B Erosion Data for 10-Minute Impingement of l-g. High-speed Fly Ash on s Radioactive Steel Alloy Sled swjaee'
Test 1 2
Ash recouered, 8.
Counting vale, c./min.
..
2
33 76 1.3 gr./fl.', ash ADat 10.5O.fl./sec.
1
3
. .
Colleeled, 8.
. .. ...
2
0.71 2253 0.54 1446 5 0.58 1479 6 0.54 2227 7 0.53 2261 1.3 gr./ft.a,ash B b at 10.0 ft./see.
0.024 0.014 0.014 0.021 0.021
2
8
0.004 0.004 0.005
4
0.23 473 $1 0. 17 423 10 0.16 502 1.6 gr./jL8, ash Bb at 8W jt./see. 11 0.23 395 12 0.26 331 13 0.28 376 1.8 gr./fL5,ash Ab at 8Wft./see.
2
*
0.004 0.003 0.003
1, flat; 2, curved. A, untreated; B, Aerotec separated. ' 0.04 g. expected. 0.015 9. exwcted.
EXAMPLE 4 TABLE 4A Summanr of Ozonolvsis RUM I V ~ no.
gas, solvent, and temperature
Critical variables in promsing
69
10% Oa/N2 in 2.83 g. X, 32 ml. HAG,20-25°C.
70
5% Oi/N9 in 0.85 g . X, CCL/HAc: 31/8 ml., 25-24% 10% Os/N2in 2.83 g. X, 32 ml. CClr, 21-24°C.
Heated 2 hr. a t 9W5"C.; half charge (5%) OJ passed through a t 2S°C. over 15-mi". period. Allowed to stand 3 dam a t 25°C.: added 15 ml. HAe: reflured 0.5 hr. Added 30 ml. HAG; heated 2 hr. at SG95'C.; 1 ml. HsO added; half charge Oa added during 30 min. a t 25°C. Held 2 hr. a t 25°C.; added 15 ml. HAc; refluxed 0.5 hr.
71
Yield,
%
Charred 80 40 77
JOURNAL OF CHEMICAL EDUCATION
592
TABLE 4B Summary of Omonolysis Runs 69 to 12 Ozoniwtion 7
Run no.
Oa/N2,
69
x,
%
.
Temp.,
"C. 20-25
9.
Solval, ml.
10
2 83
HAo 32
70
5
0 85
CCL 31 HAG 8
23-24
71
10
2 83
CCll 32
21-24
CCll 31 HAc 8
23-24
72
5
0 85
-
-
Decornporition A
OdX?,
Time,
%
Treatmat
5
Heated Oaadded Held 15 ml. HAe added Refluxed 30 ml. HAc added Heated 1 ml. HnOadded 0, added Held 15 nd. HAc added Rrthed
5
hr.
Temp., C.
Yield,
90-95 25 25
Chard
2
'14
72
% 80
'/J
40 2
M-95
'/*
25 25
2
77
'/*
Based on amount of T: used
EXAMPLE 7
EXAMPLE 5 Table 5A Some Physical Constants of the Brominated Hydrocarbons I I d
Chemical
CBn
C2H4Bh
CH3Brn C&r
Specific gravity Boiling ~ o i n t OC. ,
3.42 189.5
2.055 108
2.495 98.5
Diet B included Diet A plus 20 micrograms of X (from XCOI) per 10 g. of skim milk. Diet C was Diet A enriched with 20 micrograms of X (from X20J per 10 g. of skim milk. TABLE 7A Results of Feedina Rats Low-X Diet A* for 8 Weeks
226
TABLE 5B Soma Physical Constants of the Chlorinated Hydrocarbons Used Specific orauitv
Chemical
Ral
Starling
Weight, g. Final
Gain
-
135 168 186 165 202 lli 150 152 135 148
Roiling mint. "C
Average
EXAMPLE 6 a
63.8
See Table 1.
TABLE 6A Effect of Filter in Gas Line Time
Meter readings,
Flow mte, Temp., e. f . nz. "F.
AP across t w p ,
in. Ho
TABLE 7B Comparison of Rat Weight Gains on Thfor 8 Weeks
-X A*
B
C
Fbw rate,
..
20 20
XCO, x 2 0 1
Average
63.8 75.15 75.3
Each diet was fed to a different group of 10 rats. See Table 1.
TABLE 6B Effect of Filter in Gas Line SO-min. intewaL
added to die1 A5-
X Test Diets=
AP
Temp., OF.
across trap, in. Hg
(10)Similiar tables shonld be set u p i n the same manner within a given report. If the data of both tables in Example 5 are to appear in the same report, they should be set up in the same manner, preferably like Table 5B. (11) Il'henever posszble, a table should be set u p so that it can be typed on the page i n the normal manner.
NOVEMBER. 1954
See Example 3. (12) For ease of comparzson, a table should be set u p so that all the data in a given column have t k same unit. If the items in a column have d6fferent units, each item should be centered in the column instead qf aliped i n the usual manner by digits or the decimal point. See Example 5. (13) Data of anly record interest sl~ouldnot be included in a report table. The clock times listed in Tahle 6.4 of Example 6 are not pertinent to the prohlem. In fact, listing them oh-
593
scures the pertinent fact that the readings were made at 30-min. intervals. (14) Often a summary table should be presented in the report and the supporting or record tables may be placed in an appendix. In Example 7, Table 7B is a summary of the paragraph, of Table 7A, and of two similar tables giving the results of feeding diets B and C. Table 7A and the other two tables may be placed in an appendix to the report. Of course, such decisions are dependent upon the purpose of the report.
