Core Methods in
Educational Data Mining
HUDK4050
Fall 2015
Assignment
Q1-Q3
• Within data set 1, how many correlations are
statistically significant (according to the
customary p<0.05 definition)
– If you do not apply any sort of post-hoc control?
– If you use Bonferroni
– If you use Benjamini&Hochberg
Q4
• What is the correlation with the lowest pvalue that comes up significant for B&H but
not for Bonferroni?
Q5-Q7
• Within data set 2, how many correlations are
statistically significant (according to the
customary p<0.05 definition)
– If you do not apply any sort of post-hoc control?
– If you use Bonferroni
– If you use Benjamini&Hochberg
Q8
• What is the lowest correlation that is still
statistically significant, according to
Bonferroni’s test?
Why were the “lowest significant
correlations” so different between
data sets?
Q9
Question 9:
Now do you see why Professor Baker says that statistical
significance doesn’t matter much for really big data sets? (and
this is NOT a big data set by reckoning in other fields)
• Yes – Bonferroni is ridiculously conservative with 1,112
tests, and yet correlations that are absurdly small still
come up statistically significant.
• No. I think the answer to Question 9 is a fine correlation,
perfectly likely to represent a large effect size.
• No. Big data is a FAD. No one should ever expect to work
with a data set over 150 data points, especially after the
societal collapse predicted by James Howard Kunstler
occurs.
Today…
• We’ll discuss discovery with models
Discovery with Models
• What is discovery with models?
Discovery with Models
• How is it used in prediction?
• How is it used in relationship mining?
Discovery with Models
• Why do we need a special term for it?
(Do we need a special term for it?)
Advantages & Disadvantages
• What are some of the advantages and
disadvantages of discovery with models?
Questions or comments?
Questions or comments about Dawson
et al. case study?
Questions or comments about
Hershkovitz et al. paper?
Questions or comments about
Fancsali paper?
Any other questions about
discovery with models?
Assignment B7
• Clustering
• Any questions?
Next Class
• Tuesday, November 17
• Baker, R.S. (2015) Big Data and Education. Ch. 7, V1,
V2, V3, V4, V5.
• Amershi, S. Conati, C. (2009) Combining Unsupervised
and Supervised Classification to Build User Models for
Exploratory Learning Environments. Journal of
Educational Data Mining, 1 (1), 18-71.
• Bowers, A.J. (2010) Analyzing the Longitudinal K-12
Grading Histories of Entire Cohorts of Students:
Grades, Data Driven Decision Making, Dropping Out
and Hierarchical Cluster Analysis. Practical Assessment,
Research & Evaluation (PARE), 15(7), 1-18.
The End