How to add new user roles and capabilities?

For a plugin i’m making i need some help with selecting user roles.

I create/add some capabilities i add to existing roles which works fine. I also create a new userrole. Which also works fine.
The problem lies in selecting that role.
I’ve made a dropdown menu which lists all roles but selecting the right role often results in wrong access rights because the dropdown doesn’t work right.

My current code:

$all_roles 		= $wp_roles->roles;
$editable_roles = apply_filters('editable_roles', $all_roles);

And the dropdown:

<select name="miner_corp_statistics">
	<?php foreach($editable_roles as $role) { ?>
		<?php $capabilities = array_keys($role['capabilities']); ?>
		<option value="<?php echo current($capabilities); ?>" <?php if(in_array($miner_config['corp_statistics'], $capabilities)) { echo 'selected'; } ?>><?php echo $role['name']; ?></option>
	<?php }	unset($role);?>
</select> Minimum required userlevel to see the statistics.

This in essence works fine. But since it relies on in_array() its hardly reliable. For example if i select the subscriber role i almost always end up assigning my newly made role. Which obviously is wrong. I suspect this happens because of the capabilities assigned.

The roles and capabilities are created using this code on plugin activation:

add_role('miner_user', 'Corp Miner', array('read', 'miner_user'));
add_role('miner_supervisor', 'Corp Supervisor', array('read', 'miner_user', 'miner_supervisor'));
add_role('miner_administrator', 'Corp Administrator', array('read', 'miner_user','miner_supervisor', 'miner_administrator'));

$wp_roles->add_cap('administrator','miner_user');
$wp_roles->add_cap('administrator','miner_supervisor');
$wp_roles->add_cap('administrator','miner_administrator');

$wp_roles->add_cap('editor','miner_user');
$wp_roles->add_cap('editor','miner_supervisor');
$wp_roles->add_cap('editor','miner_administrator');

Perhaps i’m missing something, perhaps i did it wrong entirely. I’m not sure. I’ve spend all evening on the codex and google yesterday with zero results on the dropdown. I did found out my way of adding the roles and capabilities is right.

Any help is appreciated. Some tutorial, snippet, manual… Something to make this work. Thanks!