# (solution) Midterm Exam – Pre-exam data preparation – Est. Preparation

Midterm Exam ? Pre-exam data preparation ?

Est. Preparation Time ? 2 hours

Dataset Problems #1/#2                                October 3rd ? 6th Fall 2016

A significant portion of your midterm examination is based on your ability to identify, manipulate and analyze a dataset.  You should use the information found /skills developed while completing the various ?learning by doing? exercises found in modules 1 ? 10 of this course.

NOTE: You should refer to the Expected Learning Outcomes document under the Expected Learning Outcomes tab for guidance as to the types of questions you may be asked about the datasets found below.

Dataset Problem #1 ? Expected Learning Outcomes 1 ? 6.

• Open the dataset Diamonds.xls in Excel.  The link to the dataset is attached in the same place as this document.
• Review the dataset ? paying specific attention to the variables and to the source of the data (each defined in a variable definition tab).
• Identify the following features about the variables in the dataset ? type, shape, central tendency and spread of the distribution.
• Ascertain which graphical tools would be appropriate to display information about the variables in the dataset.
• Be prepared to answer the basic questions below on your exam ?
• Does the Diamonds dataset provide information on a sample or a population?
• How many observations are in the dataset?
• How many variables are in the dataset?
• Identify the type of variable (e.g., quantitative, discrete etc.)
• What type of approach do you think was used to collect the Diamonds dataset (i.e., experimental or non-experimental).  Explain your thinking for your selection.
• If you were asked to pick a random sample of 40 observations, outline the steps you will take to select the random sample.
• Develop the five-number summary for the price of diamonds in the whole dataset.
• Find the mean, median and standard deviation of overall diamond prices.
• Find the mean, median and standard deviation diamond prices as determined by each individual rater (GIA, IGI, HRD).
• Do prices for similar diamonds vary across raters?
• What graphical tool would you suggest to illustrate the answer to question ?j??
• Is there a relationship/correlation between diamond weight and diamond price?

Dataset Problem #2 ? Expected Learning Outcome 7 ? 9.

• Open the dataset Diamonds2.xls in Excel.  The link to the dataset is attached in the same place as this document.
• Review the dataset — paying specific attention to the variables and to the source of the data (each defined in a dataset tab).
• Identify whether there is a positive or negative linear relationship by examining a scatterplot and developing a regression equation (using weight as a predictor of price).
• Find the correlation coefficient between weight and price.
• Be able to display any relationship between two variables using scatter plot and/or scatter diagrams.

IDNO
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
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49 WEIGHT
0.3
0.3
0.3
0.3
0.31
0.31
0.31
0.31
0.31
0.31
0.32
0.32
0.33
0.33
0.34
0.34
0.34
0.34
0.34
0.34
0.35
0.35
0.35
0.35
0.36
0.36
0.37
0.37
0.4
0.4
0.41
0.43
0.45
0.46
0.48
0.5
0.5
0.5
0.5
0.5
0.51
0.51
0.52
0.52
0.52
0.52
0.53
0.53
0.53 COLOR
D
E
G
G
D
E
F
G
H
I
F
G
E
I
E
F
G
G
H
H
E
F
G
H
F
H
F
H
F
H
F
H
I
E
G
E
E
F
F
G
F
G
D
E
F
F
D
F
F CLARITY
VS2
VS1
VVS1
VS1
VS1
VS1
VS1
VVS2
VS2
VS1
VS1
VS2
VS2
VS2
VS1
VS1
VS1
VS2
VS1
VS2
VS1
VS1
VS1
VS2
VS1
VVS2
VS2
VS1
VS1
VS1
VS1
VVS2
VS1
VVS2
VVS2
VS1
VS1
VVS2
VS1
VS1
VVS2
VS1
VS2
VS1
VVS2
VS1
VS1
VVS2
VS1 RATER
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA PRICE
1302
1510
1510
1260
1641
1555
1427
1427
1126
1126
1468
1202
1327
1098
1693
1551
1410
1269
1316
1222
1738
1593
1447
1255
1635
1485
1420
1420
1911
1525
1956
1747
1572
2942
2532
3501
3501
3501
3293
3016
3567
3205
3490
3635
3635
3418
3921
3701
3480 50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99 0.53
0.54
0.54
0.55
0.55
0.55
0.56
0.56
0.57
0.59
0.6
0.62
0.63
0.64
0.66
0.7
0.7
0.7
0.7
0.71
0.71
0.71
0.71
0.72
0.8
0.82
0.84
0.85
0.86
0.89
0.9
0.5
0.5
0.51
0.55
0.56
0.57
0.6
0.63
0.7
0.7
0.7
0.7
0.7
0.7
0.71
0.71
0.71
0.72
0.72 G
E
F
E
F
G
F
I
G
G
F
E
G
G
H
F
G
H
I
F
F
F
H
F
I
I
H
F
H
H
I
E
G
F
H
E
H
H
E
E
F
F
F
G
H
D
E
H
E
H VVS2
VS1
VVS1
VVS2
VS1
VVS2
VS1
VVS2
VVS2
VVS2
VS1
VVS1
VVS2
VVS1
VVS1
VS1
VS1
VVS2
VS2
VVS2
VS1
VS2
VVS2
VS2
VVS2
VS2
VS2
VS2
VVS2
VS1
VVS2
VS1
VVS1
VVS1
IF
VS1
VVS1
IF
IF
VS1
VVS1
VS2
VS2
VS1
VVS2
VS1
VS1
VVS2
VS1
VVS1 GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA 3407
3767
4066
4138
3605
3529
3667
2892
3651
3773
4291
5845
4401
4759
4300
5510
5122
5122
3861
5881
5586
5193
5193
5263
5441
4948
5705
6805
6882
6709
6682
3501
3432
3851
3605
3900
3415
4291
6512
5800
6285
5122
5122
5122
5122
6372
5881
5193
5961
5662 100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149 0.73
0.73
0.73
0.73
0.73
0.74
0.74
0.75
0.75
0.75
0.76
0.77
0.78
0.8
0.83
0.9
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1.01
1.01
1.01
1.01
1.01
1.01
1.01
1.01
1.01
1.01
1.02
1.02
1.02
1.03
1.04
1.04
1.05
1.06
1.06 E
H
H
I
I
G
H
D
I
I
D
F
H
I
E
F
D
D
E
E
F
F
F
F
G
G
G
G
H
I
I
D
E
E
F
F
H
H
I
I
I
F
F
G
E
F
I
I
G
H VS2
VS1
VS1
VVS1
VS1
VVS2
VS2
VVS2
VVS2
VS1
IF
VVS1
VS1
VS2
VS2
VS1
VVS1
VS1
VS1
VS2
IF
VVS2
VS1
VS2
VVS2
VS1
VS2
VS2
VS2
VS1
VS2
VVS1
VS1
VS2
VS1
VS2
VS1
VS2
VVS1
VVS2
VS2
VS1
VS2
VVS2
VS1
VS1
IF
VVS2
VS2
VS2 GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA
GIA 5738
5030
5030
4727
4221
5815
4585
7368
4667
4355
9885
6919
5386
4832
7156
7680
15582
11419
10588
9757
13913
10588
10713
9480
9896
9619
9169
9203
8788
8095
7818
16008
10692
9853
10272
9573
9153
8873
8873
8455
7895
10372
9666
10090
10900
10571
9563
8781
9743
9302 150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199 1.07
1.1
0.18
0.18
0.18
0.18
0.18
0.18
0.19
0.19
0.19
0.19
0.19
0.19
0.19
0.19
0.2
0.2
0.2
0.2
0.21
0.21
0.21
0.21
0.22
0.23
0.23
0.23
0.24
0.25
0.25
0.25
0.25
0.26
0.26
0.26
0.26
0.27
0.27
0.28
0.29
0.29
0.3
0.3
0.3
0.3
0.3
0.31
0.31
0.31 I
H
F
F
G
G
G
H
D
E
F
F
F
G
G
H
D
G
G
G
D
E
F
G
E
E
F
G
H
F
G
H
I
F
F
F
I
F
H
I
G
I
E
F
G
H
I
E
F
I VVS2
VS2
VVS1
VVS2
IF
IF
VVS2
IF
VVS2
IF
IF
VVS1
VVS2
IF
VVS1
IF
VS1
IF
VS1
VS2
VS1
IF
IF
IF
IF
IF
IF
IF
IF
IF
IF
IF
IF
IF
VVS1
VVS2
IF
IF
IF
IF
IF
IF
VVS2
VVS2
VVS1
VVS2
IF
VVS2
VVS1
IF GIA
GIA
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI 8945
9646
823
765
803
803
705
725
967
1050
967
863
800
842
800
758
880
880
705
638
919
1149
1057
919
1198
1248
1147
995
1108
1485
1283
1149
1082
1539
1365
1260
1121
1595
1233
1199
1471
1238
1580
1459
1459
1218
1299
1628
1628
1337 200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249 0.32
0.33
0.34
0.34
0.35
0.35
0.4
0.41
0.41
0.47
0.48
0.5
0.51
0.51
0.52
0.55
0.56
0.56
0.58
0.58
0.58
0.7
0.7
0.71
0.76
0.78
1
1.01
1.01
1.01
0.5
0.5
0.51
0.52
0.52
0.53
0.53
0.55
0.56
0.56
0.57
0.57
0.58
0.6
0.6
0.6
0.61
0.62
0.64
0.65 H
H
F
F
F
G
G
I
I
F
F
G
E
F
I
F
E
G
E
F
G
G
G
D
F
G
H
G
H
I
F
G
F
E
H
F
F
G
F
F
F
H
H
G
G
H
H
I
H
I IF
IF
VVS1
VVS2
VVS1
VVS2
IF
VVS1
VVS2
VVS2
VS1
IF
VVS2
VVS1
IF
VVS2
VVS2
VVS2
VVS1
VVS1
VVS1
VVS1
VVS2
VS1
VVS2
VVS2
VVS2
VS1
VS2
VS1
VVS1
VVS1
VVS1
VS2
VVS1
VVS1
VVS2
VVS2
VS1
VS2
VS2
VVS1
IF
VS1
VS2
VVS1
VVS2
VVS2
VVS2
VVS2 IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
IGI
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD 1462
1503
1773
1636
1821
1540
2276
1616
1506
2651
2383
3652
3722
3722
3095
3706
4070
3470
4831
4209
3821
5607
5326
6160
6095
5937
9342
9713
8873
8175
3778
3432
3851
3346
3130
3995
3701
3529
3667
3202
3256
3415
3792
3925
3421
3925
3616
3615
3785
3643 250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299 0.66
0.7
0.7
0.7
0.7
0.7
0.71
0.71
0.72
0.73
0.73
0.74
0.8
0.8
0.8
0.8
0.8
0.81
0.81
0.81
0.81
0.81
0.82
0.82
0.85
0.85
0.85
0.86
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1.01
1.01
1.01
1.01
1.01
1.01 H
E
E
G
G
H
G
H
H
F
G
H
F
F
G
H
H
E
E
F
G
H
F
G
F
F
G
H
D
E
E
E
F
F
G
G
G
H
H
H
I
I
I
I
D
E
E
F
F
G VVS1
VVS1
VVS2
VVS1
VVS2
VS2
IF
VVS2
VVS1
VS2
VVS1
VVS1
IF
VS1
VVS2
VVS2
VS1
VVS1
VS2
VS1
VS1
IF
VS2
VVS2
VVS1
VS2
VVS1
VS2
VVS2
VVS1
VVS2
VS1
VVS1
VVS2
VVS1
VVS2
VS2
VVS1
VS1
VS2
VVS1
VVS2
VS1
VS2
VVS2
VVS2
VS1
VVS1
VS1
VVS2 HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD 4300
6867
6285
5800
5510
4346
6372
5193
5662
5333
6041
5815
8611
6905
6905
6416
6051
8715
6988
6988
6495
7358
6572
7072
8359
6805
7711
5835
13775
14051
11419
10588
11696
10588
10450
9896
9203
9480
9065
8788
8788
8372
8095
7818
13909
11531
10692
11811
10272
9993 300
301
302
303
304
305
306
307
308 1.01
1.01
1.01
1.01
1.01
1.02
1.06
1.02
1.09 G
H
H
I
I
F
H
H
I VS2
VVS2
VS1
VVS1
VS1
VVS2
VVS2
VS2
VVS2 HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD
HRD 9293
9433
9153
8873
8175
10796
9890
8959
9107 Data are for 308 round-cut diamonds, taken from a newspaper ad
Data were obtained from the Journal of Statistics Education data archive
IDNO – an identification number for each data point (NOTE This is not a variable)
WEIGHT – weight of the diamond, in carats
COLOR – degree of color purity in the diamond
&quot;D&quot; represents top color purity grade
Lesser grades are &quot;E&quot;, &quot;F&quot;, and so on, through the alphabet CLARITY – diamond clarity (presence or absence of minute flaws)
&quot;IF&quot; means &quot;internally flawless&quot; – the top grade. No flaws visible under 10-power mag