I would say that the contrast offered between the boorish sweeping generalisations of the men conducting the "investigation" and the methodical psychological profiling used by the women, Mrs Peters and Mrs Hale, to piece together the events of the murder of Mr Wright is the most compelling and obvious technique employed by Glaspell.
We see the men's dismissive attitude of the women who are constantly -
worrying over trifles,
when in fact they are carefully recreating the last movements of Minnie Wright. There is a great irony in that the women establish the disturbed state of Mrs Wright by the erratic stitching of the last piece of her quilt, and yet the sherriff asks -
would the women know a clue if they did come upon it?
The contrast in enhanced by the women not only ascertaining the true crime, and Mrs Wright's motive for murder, but also being able to conceal the true events from the menfolk in order to protect one of their own.