I have used and supported SPSS since 1975 but due to rulings within the University the Computing Centre / IT Services were not allowed to give statistical advice so I have concentrated on data management and charts and graphs and let what little statistical knowledge I had lapse; so when a user presented me with this problem I’m stuck. Please would someone be kind enough to explain the apparent, to him, discrepancies ? I assume it is to do with rounding during the calculations ?
I want to check how SPSS treats the mode average. I have found it can do this (via the frequencies) option but seems to consistently get it wrong – i.e. it always chooses the one after the mode (so if the mode – most frequent – answer was 0 it returns a 1). Compare the mode below for single authored articles with the frequencies data. I am worried the same error is creeping into the medians. For example, for co-authored articles I can’t see how the median (middle) entry could be 1 when 77% odd of the respondents answered 0.
Perhaps I’m misunderstanding the stats, perhaps there is something about the way SPSS is using the data, but I want to make sure there is not a generalised error inflating the stats (which could lead to serious egg on face later!)
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Statistics |
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How many single or co-authored journal articles have you ... |
How many of these were published in journals outside of t... |
How many co-authored journal publications have you publis... |
How many articles did you publish prior to recieving an academic post with research in the contract? |
What is the largest number of single and co-authored jour... |
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|
N |
Valid |
240 |
238 |
226 |
239 |
242 |
|
Missing |
14 |
16 |
28 |
15 |
12 |
|
|
Mean |
4.66 |
2.57 |
1.38 |
3.85 |
3.20 |
|
|
Std. Error of Mean |
.204 |
.127 |
.068 |
.187 |
.079 |
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|
Median |
4.00 |
2.00 |
1.00 |
3.00 |
3.00 |
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|
Mode |
3 |
1 |
1 |
1a |
3 |
|
|
Std. Deviation |
3.154 |
1.960 |
1.019 |
2.890 |
1.227 |
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Skewness |
2.353 |
2.178 |
4.235 |
1.293 |
2.241 |
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Std. Error of Skewness |
.157 |
.158 |
.162 |
.157 |
.156 |
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Kurtosis |
7.396 |
6.356 |
21.849 |
1.031 |
10.834 |
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|
Std. Error of Kurtosis |
.313 |
.314 |
.322 |
.314 |
.312 |
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Minimum |
1 |
1 |
1 |
1 |
1 |
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Maximum |
21 |
12 |
9 |
12 |
12 |
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Sum |
1118 |
612 |
313 |
921 |
775 |
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a. Multiple modes exist. The smallest value is shown |
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How many single or co-authored journal articles have you ... |
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Frequency |
Percent |
Valid Percent |
Cumulative Percent |
|
|
Valid |
0 |
12 |
4.7 |
5.0 |
5.0 |
|
1 |
29 |
11.4 |
12.1 |
17.1 |
|
|
2 |
62 |
24.4 |
25.8 |
42.9 |
|
|
3 |
51 |
20.1 |
21.3 |
64.2 |
|
|
4 |
26 |
10.2 |
10.8 |
75.0 |
|
|
5 |
18 |
7.1 |
7.5 |
82.5 |
|
|
6 |
17 |
6.7 |
7.1 |
89.6 |
|
|
7 |
2 |
.8 |
.8 |
90.4 |
|
|
8 |
7 |
2.8 |
2.9 |
93.3 |
|
|
9 |
2 |
.8 |
.8 |
94.2 |
|
|
10 |
2 |
.8 |
.8 |
95.0 |
|
|
11 |
3 |
1.2 |
1.3 |
96.3 |
|
|
12 |
3 |
1.2 |
1.3 |
97.5 |
|
|
14 |
2 |
.8 |
.8 |
98.3 |
|
|
15 |
1 |
.4 |
.4 |
98.8 |
|
|
16 |
1 |
.4 |
.4 |
99.2 |
|
|
20 |
2 |
.8 |
.8 |
100.0 |
|
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Total |
240 |
94.5 |
100.0 |
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|
|
Missing |
System |
14 |
5.5 |
|
|
|
Total |
254 |
100.0 |
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How many co-authored journal publications have you publis... |
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Frequency |
Percent |
Valid Percent |
Cumulative Percent |
|
|
Valid |
0 |
176 |
69.3 |
77.9 |
77.9 |
|
1 |
36 |
14.2 |
15.9 |
93.8 |
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|
2 |
6 |
2.4 |
2.7 |
96.5 |
|
|
3 |
1 |
.4 |
.4 |
96.9 |
|
|
4 |
3 |
1.2 |
1.3 |
98.2 |
|
|
5 |
2 |
.8 |
.9 |
99.1 |
|
|
6 |
1 |
.4 |
.4 |
99.6 |
|
|
8 |
1 |
.4 |
.4 |
100.0 |
|
|
Total |
226 |
89.0 |
100.0 |
|
|
|
Missing |
System |
28 |
11.0 |
|
|
|
Total |
254 |
100.0 |
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Dr Andrew Dilley
Lecturer in History
http://www.abdn.ac.uk/history/staff/details.php?id=a.dilley
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