Table B gives the approximate number of percentage points by which two observed percentages must differ in order for the reader to infer that the true percentages in the populations or subgroups are different with a confidence of approximately .90. In other words, if the observed difference exceeds the value given at the intersection of the appropriate row and column in the table, it may be stated with approximately 90 percent confidence that the true percentages in the populations are different.

The appropriate section of the table to use is determined by the larger of the two sample percentages being examined. The appropriate row and column within a section are determined by the sample sizes of the larger percentage and the smaller percentage, respectively. The value at the intersection of the appropriate row and column must be exceeded by the difference between the two sample percentages in order for the sample difference to be significant at approximately the .90 level of confidence.

To illustrate the use of Table B, suppose we are interested in knowing if there is a difference between the percentage of men teachers and the percentage of women teachers who feel that the community in which they teach does not place any special restrictions on them because they are teachers. The sample data presented show 48.6 percent of the men and

45.7 percent of the women teachers felt no personal restrictions. Is this sample difference of 2.9 percentage points large enough to indicate a true difference in the population percentages for men and women? Since the larger of the two percentages (48.6) is near 50 percent, we select the section of Table B headed "Larger percent near 50 percent." The sample size on which this percentage is based is 420 men so we select the row labeled "Sample size of larger percentage 500." Since the sample size on which the smaller percentage is based is 965 we select the column headed 1,000. At the intersection of this row and column we find the value 4.5 percentage points. This means that we must have a difference of more than this to represent a true difference in the population percentages. Since the difference between the sample percentages was only 2.9 percentage points, we can conclude that this much difference could easily be due to sampling variation and that there is actually no difference between the percentage of men and the percentage of women in the population who feel unrestricted by the communities.

Interpolation between sample sizes and between sections of the table may be used for other percentages and sample sizes not given in the table. Statements made on the basis of a value obtained from the table by interpolation should be made with caution since the confidence level may be lower than .90.

INDEX

Ability grouping: elementary, 7; secondary, 7
Academic work: amount of, 15

Achievement: grouping by, elementary 7; group-
ing by, secondary, 7; reporting of scores, 35;
yesterday and today, 16

Admission: early for girls, 36
Age for leaving school, 20

Assignment: of new teachers, 47-48; qualifica-

tions for, 46; of teachers to slum schools, 48
Athletics: emphasis on, 32

Automobiles: policy for students, 39

nationwide, 47

Certification of teachers:
Characteristics of teachers: age, 52, annual
salary, 54; class enrollment, 53; degrees, 52;
experience, 53; marital status, 52; number
of classes a day, 54; sex, 52; teaching as-
signment, 53; teaching field, 54
Class size: best for elementary school, 8;
elementary, 8; technological advancement
and, 28; television and, 28; with and with-
out clerical help, 8-9

Communism: teaching about, 13
Community reactions: personal restrictions on
teachers, 46; political activities of teach-
ers, 50-51; teachers' prestige, 44-45; to
teaching about communism, 13; to teaching
about the UN, 13

Controversial topics in the classroom: sex
education, 13-14; teaching about commu-
nism, 13; teaching about the UN, 13
Corporal punishment, 18; see also Discipline
Criticism of education: amount of academic

work, 15; amount of exercise, 32; corporal
punishment, 18; emphasis on sports, 32-33;
neglect of the gifted, 26; and Russian ad-
vances in space, 15-16; sex education, 13-14;
teaching about communism, 13; teaching about
the UN, 13

De facto segregation, 17

Discipline: corporal punishment, 18; maintain-

ing discipline, 19; trouble makers, 18-19
Dress: standards for students, 38

Dropouts: legal age, 20

Duty-free lunch periods for teachers, 49

Examinations: influence of college entrance
examinations, 27; influence of Merit schol-
arships, 27

Exercise: amount of time for, 32; see also
Physical education

Federal aid to education: for counseling and
guidance, 21; general, 21-22; for higher
education, 22-23; for nonpublic schools, 22;

guidance, 21; science and mathematics, 21;
see also Federal aid to education

Nonpublic schools: federal aid to, 22

Physical education: emphasis on sports, 32-33;
time allotment for, 32

Politics and the teacher: national elections, 50;
political philosophy, 51; state elections, 50;
taking sides, 50-51

Preparation of teachers, 41-43
Prestige of teachers, 44-45
Professional status of teachers: men in teach-
ing, 45; nationwide certification, 47; teach-
er prestige, 44-45; teacher qualifica-
tions, 46; teaching as a profession, 44; see
also Teachers

Promotion policy: in elementary school, 34

Qualifications of teachers, 46

Regulations, student: school attendance by the
married, 38; smoking, 39-40; standards of
dress, 38; use of automobiles, 39

Salaries: and federal aid for, 22; merit pay, 31
Segregation: de facto, 17

Sex education, 13-14

Shared time, 37

Slum schools: staffing of, 48

Smoking: by students, 39-40

Student regulations: see Regulations, student Study habits: effects of TV on, 10; see also Homework

Teacher aid and class size, 8-9

Teachers: adequacy of preparation, 41-42;

amount of preparation, 42-43; assignment of
new teachers, 47-48; duty-free lunch peri-
ods, 49; maintaining discipline, 19; men, 45;
morale and Mr. Novak series, 11-12; politi-
cal activity, 50-51; political philosophy, 51;

portrayal on TV, 11-12; prestige, 44-45; qualifications of, 46; restrictions on, 46 Teaching as a profession: status 44; see also Teachers

Television: and class size, 28; moral values, 10; Mr. Novak series, 11-12; and moral values, 10; and quality of education, 28; and study habits, 10; see also Instructional materials

Test scores: grouping by, 7; reporting to parents, 35

Testing programs, national: influence of, 27 Textbooks at public expense, 28-29