Changing selection in a select with the Chosen plugin

My answer is late, but i want to add some information that is missed in all above answers.

1) If you want to select single value in chosen select.

$('#select-id').val("22").trigger('chosen:updated');

2) If you are using multiple chosen select, then may you need to set multiple values at single time.

$('#documents').val(["22", "25", "27"]).trigger('chosen:updated');

Information gathered from following links:
1) Chosen Docs
2) Chosen Github Discussion

From the "Updating Chosen Dynamically" section in the docs: You need to trigger the 'chosen:updated' event on the field

$(document).ready(function() {

    $('select').chosen();

    $('button').click(function() {
        $('select').val(2);
        $('select').trigger("chosen:updated");
    });

});

NOTE: versions prior to 1.0 used the following:

$('select').trigger("liszt:updated");