Chapter 5.3
Name___________________________________
simple random sample (SRS) – sample of n people chosen in such a way that each person in the population
has the same chance of being chosen and every set of n individuals has an equal chance to be in the sample
actually selected.
systematic sample – sample chosen by first numbering every individual in the population and then choosing
every 5th or10th person, or every 23nd person, etc.
stratified sample – sample chosen by first dividing the population into smaller homogeneous groups based on
some characteristic (such as education, gender, age, etc) and then choosing the sample size from each of these
groups to form the sample.
quota sample – sample chosen by first dividing the population into small homogeneous groups based on some
characteristic (such as gender, age, education, etc) and then choosing proportionally from each group to reflect
the same characteristic in the population.
probability sample – any sample which relies on random chance in some form to choose a sample. All of the
above fall under this category. Convenience samples and voluntary response samples do not.
We are going to use the 100 people listed in the Data Bank as our population.
1.
SIMPLE RANDOM SAMPLE
RANDOM NO.
Use n = 5
Use the Table of Random Digits. Start at Line 125 and read
across. Record the first five 2-digit numbers between ____
and _____.Then list the corresponding weights from the Data
Bank. (If the same number appears a second time, discard it.)
Finally, find the sample mean.
WEIGHT
#1
#2
#3
#4
#5
SAMPLE MEAN =
Line 125: 9 6 7 4 6 1 2 1 4 9 3 7 8 2 3 7 1 8 6 8 1 8 4 4 2 3 5 1 1 9 6 2 1 0 3 3 9 2 4 4
2.
SYSTEMATIC SAMPLE
Use n = 5
TotalNumberofValues 

 
SampleSize

The first value must be a random number between 01 and
______ (answer above). Use the Table of Random Digits,
starting at Line 125; go across the row until you find the first
2-digit number between ____ and ____, inclusive. The
random number would be _____. Start at this number in the
table below to generate your list — find every ____th number.
Then list the corresponding weights and find the sample
mean.
NUMBER
WEIGHT
#1
#2
#3
#4
#5
Sample Mean =
Line 125: 9 6 7 4 6 1 2 1 4 9 3 7 8 2 3 7 1 8 6 8 1 8 4 4 2 3 5 1 1 9 6 2 1 0 3 3 9 2 4 4
3.
STRATIFIED SAMPLE
We can divide the data into ___ subgroups based on gender.
There are 50 males and 50 females in the Data Bank. Since
we want 6 values, we need to choose ____ values from each
subgroup. Use the Table of Random Digits to select which
males and females to use. Start with Line 125 and choose
the first three 2-digit numbers between ____ and ____.
These will be the males for our sample. (Note: We can count
only males, so we cannot use the ID number for this. If our
first random number is 23, then we must find the 23rd male in
the group, not ID #23.) Continue in the table where you left
off and find the next three 2-digit numbers between ___ and
____.
These will be the females for our sample. Find
corresponding weights and sample mean.
Note: If the same 2-digit number appears a second time
a 7subgroup,
Line 125within
: 96
4 6 1 2 1it 4should
9 3 7be8 2discarded.
3 7 1 8 6If8 it 1appears
8 4 4 2a
second time in a difference subgroup, it can be used again.
4.
STRATIFIED SAMPLE
RANDOM NO.
Use n = 6
Use n = 10
In our Data Bank, the 100 individuals are classified by
marital status. 20% of the people are single, 40% are
married, 20% are divorced and 20% are widowed.
Stratified sampling says that our sample should reflect this,
that 20% of our sample should be single, 40% married, etc.
Male
Female
Sample Mean =
35119 62103 39244
SUBGROUP
RANDOM NO.
Single
Married
So we need to choose ___ people for single, ___ people for
married, ___ people for divorced and ___ people for
widowed.
For the single people, we can use random numbers between
01 and 20 inclusive and choose the first two from the
Random Digit Table. If we choose 07 for instance, then we
need to find the 7th single person in the list (Person #38).
Once we find the singles, continue on that line with the new
assignment of digits looking for married.
WEIGHT
Divorced
Widowed
Sample Mean =
For single, assign random digits 01 to 20 .
For married, assign random digits 01 to _40.
For divorced, assign random digits _01_ to 20__.
For widowed, assign random digits _01_ to _20_.
Locate corresponding values in Data Bank. Then find the
sample mean.
Line 125: 9 6 7 4 6 1 2 1 4 9 3 7 8 2 3 7 1 8 6 8 1 8 4 4 2 3 5 1 1 9 6 2 1 0 3 3 9 2 4 4
Line 126: 9 6 9 2 7 1 9 9 3 1 3 6 8 0 9 7 4 1 9 2 7 7 5 6 7 8 8 7 4 1 4 8 4 0 9 4 1 9 0 3
Line 127: 4 3 9 0 9 9 9 4 7 7 2 5 3 3 0 6 4 3 5 9 4 0 0 8 5 1 6 9 2 5 8 5 1 1 7 3 6 0 7 1
WEIGHT
DATA BANK Chapter 5-3
ID#
AGE
SEX
WT
IQ
SOD
MS
ID#
AGE
SEX
WT
IQ
SOD
MS
ID#
AGE
SEX
WT
IQ
SOD
MS
ID#
WT
IQ
SOD
MS
01
72
F
120
118
136
W
26
25
M
143
103
135
M
51
67
F
160
116
146
W
76
72
M
147
114
134
W
02
18
M
145
105
137
S
27
31
M
152
119
136
D
52
42
F
109
103
144
M
77
31
M
152
126
138
M
03
42
F
118
115
135
M
28
58
F
119
116
138
M
53
19
M
131
112
133
S
78
58
F
112
123
133
M
04
33
M
162
108
142
M
29
23
F
111
105
135
S
54
25
M
153
119
149
D
79
36
M
190
121
147
M
05
19
F
106
106
133
S
30
47
F
149
123
136
M
55
41
M
165
131
152
M
80
43
M
179
131
145
D
06
56
F
143
111
138
M
31
47
M
179
113
139
D
56
24
F
112
100
132
S
81
21
F
117
105
137
S
07
65
M
160
99
140
W
32
59
M
206
99
143
W
57
32
F
115
109
136
S
82
32
F
125
119
135
M
08
36
M
215
106
151
M
33
36
M
191
118
145
D
58
50
M
173
126
146
D
83
29
F
123
116
131
D
09
43
F
127
111
134
M
34
59
F
156
100
132
M
59
32
M
186
122
149
M
84
59
M
185
127
144
W
10
47
F
132
109
135
D
35
63
F
122
106
135
W
60
26
M
181
121
142
S
85
24
M
133
114
129
M
11
48
M
196
115
146
D
36
29
M
175
121
148
M
61
36
F
112
98
135
D
86
36
M
163
119
139
M
12
25
F
109
114
141
M
37
43
M
194
129
146
S
62
40
F
130
105
136
D
87
34
F
135
117
135
D
13
63
F
170
101
152
D
38
44
F
132
109
132
S
63
19
M
132
111
137
S
88
36
F
142
88
137
D
14
37
M
187
109
144
W
39
63
M
188
121
145
M
64
37
F
179
127
141
M
89
29
M
155
98
135
S
15
40
M
234
98
147
M
40
36
F
125
117
140
M
65
65
M
212
129
148
M
90
42
M
169
96
137
M
16
25
M
199
103
148
S
41
45
F
109
102
136
M
66
21
F
99
103
131
S
91
41
F
136
102
141
D
17
72
F
143
103
145
W
42
71
F
112
123
133
W
67
25
F
128
121
131
S
92
69
F
112
102
130
W
18
56
F
156
99
144
D
43
57
M
167
103
143
W
68
68
M
167
98
140
W
93
43
M
185
100
143
M
19
37
M
142
110
135
D
44
20
F
101
111
125
S
69
18
F
121
113
136
S
94
61
M
173
101
141
M
20
61
F
123
108
134
M
45
24
F
106
114
127
D
70
26
M
163
99
140
D
95
21
F
106
105
131
M
21
33
M
165
112
137
M
46
42
M
148
107
140
S
71
45
M
185
101
143
M
96
56
F
149
103
141
S
22
52
M
157
106
134
D
47
55
F
170
106
130
W
72
44
F
130
128
137
W
97
63
M
192
95
147
M
23
44
F
121
116
133
M
48
63
M
152
95
142
M
73
50
F
142
104
138
M
98
74
F
162
99
151
W
24
53
F
131
121
136
W
49
65
M
191
115
147
W
74
63
F
166
103
147
W
99
35
F
151
113
145
M
25
19
M
128
122
132
S
50
28
M
148
100
135
M
75
48
M
163
103
144
W
100
28
M
161
116
138
M
AGE: in years.
AGE SEX
SEX: male (M) or female (F). WT: Weight in pounds. IQ: in standard IQ test score values. SOD: Sodium is given in milliequivalents per liter
MS: Marital Status defined as: S = single, M = married, W = widowed, D = divorced.