For a task on data cleaning and analysis using SPSS I have two research questions for which I should pick an appropriate statistical test. It's been over a few years though since my last statistics course and I feel like some sources are contradicting each other.

The first question is whether there's a relationship between two paired ordinal variables, more specifically, these variables are the Apgar-scores at 1 minute and 5 minutes, used in obstetrics.

My first intention was to use Wilcoxon signed-ranks test, due to the description of the variables. But my statistics notes of back in the days mention a few times that when searching a relationship it is preferred to use correlation, rather than Wilcoxon, which would be more preferred when searching a difference. If it is correct to search correlation, I assume this would be the Spearman's rank correlation coefficient, due to the ordinal character of the variables.

As for the second question, is to find whether there's a difference in the need of extra care (nominal) when the duration of pregnancy is accounted for. The duration of pregnancy is divided into two categories, either less than 37 weeks or between 37 and 42 weeks. Due to the rather obvious greater than/lesser than character of the latter, I interpreted this as an ordinal variable.

Because I'm working with two categorical variables here, I was rooting for a Chi-squared test, but, as I heard from my colleagues, a binary logistic regression would also be possible, I never learnt anything about the latter in the past, so I don't know if this would be a better fit.

Thanks in advance.

  • $\begingroup$ For the first question, I'd suggest Spearman's rank correlation. Because you're using SPSS, perhaps see this page. For the second question, I understand the two levels Long/Short pregnancy for one variable. But what is the other variable? Some quantitative measure of extra care required? $\endgroup$ – BruceET Mar 2 '17 at 18:30
  • $\begingroup$ @BruceET Great page, thanks for the link! It is basically just a variable that indicates whether more than usual care had to be provided than you'd expect for the average birth, with a simple yes/no answer. $\endgroup$ – LD94 Mar 2 '17 at 19:36
  • $\begingroup$ Then the 2nd is a 2-by-two table: columns Long/Short, rows Yes/No. With lots of data, chi-squared test of independence. With few observations, consider Fisher Exact Test. $\endgroup$ – BruceET Mar 2 '17 at 20:36

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