PCA Example 2: Duchenne Muscular Dystrophy

Descriptive Statistics
  N Minimum Maximum Mean Std. Deviation
age 73 20 59 30.82 7.95
creatine kinase 73 15.0 657.0 95.479 123.162
hemopexin 73 53.0 118.0 86.319 13.658
lactate dehydrogenase 73 3.5 110.0 18.933 15.982
pyruvate kinase 73 87.0 412.0 203.411 68.269

 

Matrix of scatter plots, with cases marked by carrier status

Matrix of age creatkin hemopex lactdehy pyrukin by carrier

 

 

The next table shows the correlation coefficients (and p values) for the pairs of variables. Significant correlations are marked with one or more asterisks.

 

Note the pattern of correlations. In particular, pyruvate kinase is significantly correlated with all other variables. Think about how this might impact on the subsquent PCA.

  age creatine kinase hemopexin lactate dehydrogenase
creatine kinase r 0.178
p 0.132
hemopexin r **0.368 0.222
p 0.001 0.059
lactate dehydrogenase r 0.073 **0.821 0.216
p 0.540 0.000 0.067
pyruvate kinase r *0.274 **0.545 **0.371 **0.617
p 0.019 0.000 0.001 0.000
* Correlation is significant at the 0.05 level (2-tailed) .** Correlation is significant at the 0.01 level (2-tailed).

On to the first analysis.

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