</p>
</dd>
<dt>drandd</dt><dd><p>factor. Indicates a zero R&amp;D stock.</p>
</dd>
<dt>randd</dt><dd><p>numeric. R&amp;D stock (in millions of dollars).</p>
</dd>
<dt>employment</dt><dd><p>numeric. Employment (in 1000s).</p>
</dd>
<dt>sp500</dt><dd><p>factor. Membership of firms in the S&amp;P500 index.</p>
</dd>
<dt>tobinq</dt><dd><p>numeric. Tobin's q.</p>
</dd>
<dt>value</dt><dd><p>numeric. Stock market value.</p>
</dd>
<dt>institutions</dt><dd><p>numeric. Proportion of stock owned by institutions.</p>
<