Suggested answer to exercise: Checking student data, 1

Question 1: Using SPSS, look at the frequencies for the head circumference data. What two characteristics of the data does this reveal?

Suggested answer

Using Descriptive Statistics, Frequencies, and choosing the variables head circ1 and head circ 2, we get:

Statistics
head circ 1 head circ 2
N Valid 316 309
Missing 0 7

Frequency Table

head circ 1
Frequency Percent Valid Percent Cumulative Percent
Valid 80.00 2 .6 .6 .6
84.00 1 .3 .3 .9
520.00 1 .3 .3 1.3
522.00 1 .3 .3 1.6
523.00 1 .3 .3 1.9
525.00 4 1.3 1.3 3.2
526.00 2 .6 .6 3.8
530.00 2 .6 .6 4.4
531.00 1 .3 .3 4.7
532.00 2 .6 .6 5.4
533.00 5 1.6 1.6 7.0
535.00 3 .9 .9 7.9
537.00 1 .3 .3 8.2
540.00 12 3.8 3.8 12.0
545.00 10 3.2 3.2 15.2
546.00 2 .6 .6 15.8
549.00 3 .9 .9 16.8
550.00 21 6.6 6.6 23.4
551.00 1 .3 .3 23.7
552.00 2 .6 .6 24.4
553.00 1 .3 .3 24.7
554.00 4 1.3 1.3 25.9
555.00 10 3.2 3.2 29.1
556.00 1 .3 .3 29.4
557.00 4 1.3 1.3 30.7
558.00 2 .6 .6 31.3
560.00 34 10.8 10.8 42.1
561.00 5 1.6 1.6 43.7
562.00 4 1.3 1.3 44.9
563.00 1 .3 .3 45.3
564.00 5 1.6 1.6 46.8
565.00 11 3.5 3.5 50.3
567.00 1 .3 .3 50.6
568.00 2 .6 .6 51.3
569.00 3 .9 .9 52.2
570.00 34 10.8 10.8 63.0
571.00 4 1.3 1.3 64.2
572.00 1 .3 .3 64.6
573.00 4 1.3 1.3 65.8
574.00 3 .9 .9 66.8
575.00 16 5.1 5.1 71.8
576.00 2 .6 .6 72.5
577.00 1 .3 .3 72.8
578.00 1 .3 .3 73.1
580.00 31 9.8 9.8 82.9
581.00 1 .3 .3 83.2
582.00 5 1.6 1.6 84.8
585.00 6 1.9 1.9 86.7
587.00 2 .6 .6 87.3
588.00 1 .3 .3 87.7
590.00 13 4.1 4.1 91.8
591.00 1 .3 .3 92.1
592.00 3 .9 .9 93.0
593.00 1 .3 .3 93.4
594.00 1 .3 .3 93.7
595.00 2 .6 .6 94.3
596.00 1 .3 .3 94.6
598.00 3 .9 .9 95.6
600.00 4 1.3 1.3 96.8
605.00 2 .6 .6 97.5
610.00 1 .3 .3 97.8
620.00 1 .3 .3 98.1
622.00 1 .3 .3 98.4
625.00 2 .6 .6 99.1
630.00 1 .3 .3 99.4
645.00 1 .3 .3 99.7
670.00 1 .3 .3 100.0
Total 316 100.0 100.0

head circ 2
Frequency Percent Valid Percent Cumulative Percent
Valid 56.00 1 .3 .3 .3
59.00 1 .3 .3 .6
78.00 1 .3 .3 1.0
360.00 2 .6 .6 1.6
390.00 1 .3 .3 1.9
510.00 1 .3 .3 2.3
525.00 2 .6 .6 2.9
530.00 7 2.2 2.3 5.2
531.00 1 .3 .3 5.5
532.00 2 .6 .6 6.1
535.00 3 .9 1.0 7.1
536.00 1 .3 .3 7.4
539.00 3 .9 1.0 8.4
540.00 10 3.2 3.2 11.7
541.00 1 .3 .3 12.0
542.00 4 1.3 1.3 13.3
543.00 1 .3 .3 13.6
545.00 5 1.6 1.6 15.2
546.00 1 .3 .3 15.5
547.00 4 1.3 1.3 16.8
549.00 2 .6 .6 17.5
550.00 15 4.7 4.9 22.3
551.00 3 .9 1.0 23.3
552.00 3 .9 1.0 24.3
554.00 6 1.9 1.9 26.2
555.00 12 3.8 3.9 30.1
556.00 1 .3 .3 30.4
557.00 3 .9 1.0 31.4
558.00 1 .3 .3 31.7
559.00 1 .3 .3 32.0
560.00 43 13.6 13.9 46.0
561.00 2 .6 .6 46.6
562.00 6 1.9 1.9 48.5
563.00 3 .9 1.0 49.5
564.00 1 .3 .3 49.8
565.00 17 5.4 5.5 55.3
567.00 2 .6 .6 56.0
568.00 2 .6 .6 56.6
569.00 1 .3 .3 57.0
570.00 22 7.0 7.1 64.1
571.00 2 .6 .6 64.7
572.00 2 .6 .6 65.4
573.00 3 .9 1.0 66.3
574.00 1 .3 .3 66.7
575.00 16 5.1 5.2 71.8
576.00 1 .3 .3 72.2
577.00 1 .3 .3 72.5
578.00 2 .6 .6 73.1
580.00 23 7.3 7.4 80.6
581.00 1 .3 .3 80.9
582.00 3 .9 1.0 81.9
583.00 1 .3 .3 82.2
584.00 2 .6 .6 82.8
585.00 6 1.9 1.9 84.8
586.00 3 .9 1.0 85.8
587.00 1 .3 .3 86.1
590.00 12 3.8 3.9 90.0
591.00 1 .3 .3 90.3
592.00 2 .6 .6 90.9
593.00 2 .6 .6 91.6
594.00 1 .3 .3 91.9
595.00 4 1.3 1.3 93.2
598.00 1 .3 .3 93.5
599.00 1 .3 .3 93.9
600.00 4 1.3 1.3 95.1
604.00 1 .3 .3 95.5
605.00 1 .3 .3 95.8
606.00 2 .6 .6 96.4
610.00 4 1.3 1.3 97.7
620.00 1 .3 .3 98.1
625.00 3 .9 1.0 99.0
630.00 2 .6 .6 99.7
650.00 1 .3 .3 100.0
Total 309 97.8 100.0
Missing System 7 2.2
Total 316 100.0

There are two features to note:

  1. For each measurement, there are some observations which are impossible for adult head circumference in milimetres. Examples are 80 and 84 mm for head circ 1.
  2. There is clear digit preference. Both zero and five appear as terminal digits far more often that any others.

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Last updated: 18 January, 2012.

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