When using the placeholder attribute in HTML5 has there been any research into how the content of the placeholder affects the usability of the form?

I'm thinking specifically about using the placeholder attribute to replace the label attribute compared to using the placeholder attribute to replace the label attribute but provide example form content, like so...

<input placeholder="University">

<input placeholder="Harvard, Brown, Yale etc">

I'm also curious as to whether there is any research between using a label and a placeholder in a set-up that provides a descriptive label alongside example form content, compared to either just using a label or just using a placeholder attribute...

<label>University</label>
<input placeholder="Harvard, Brown, Yale etc">

<label>University</label>
<input>

<input placeholder="University">

When using the placeholder attribute in HTML5 has there been any research into how the content of the placeholder affects the usability of the form?

I'm thinking specifically about using the placeholder attribute to replace the label attribute compared to using the placeholder attribute to replace the label attribute but provide example form content, like so...

<input placeholder="University">

<input placeholder="Harvard, Brown, Yale etc">

I'm also curious as to whether there is any research between using a label and a placeholder in a set-up that provides a descriptive label alongside example form content, compared to either just using a label or just using a placeholder attribute...

<label>University</label>
<input placeholder="Harvard, Brown, Yale etc">

<label>University</label>
<input>

<input placeholder="University">

EDIT: I forgot to define the use case that I'm currently using which is using labels and placeholder attributes but the labels are hidden, so still being accessible by screen readers, just not visible on the screen.