Lead conversion rate is the percentage of leads that become customers.

Qualified leads are those continuing to engage with your messages after they sign up for your email or messenger lists. Use the open rates of “welcome” emails, or follow-up call response rates to estimate the qualified lead percentage.

Email Sequence Completion Rate is the percentage of people who engage with your messages all the way through to your sales offer.

It's an estimate of the percentage of people you expect to purchase your product or service from your Google ads campaign.

Return on marketing investment or ROMI is a metric used in online marketing to measure the effectiveness of a marketing campaign. It examines results concerning the specific marketing objective. ROMI is a subcategory of return on investment (ROI) because it's cost is specific to marketing.
As a percentage ratio, ROMI demonstrates profitability or waste of a concrete sum of money invested. It is calculated with the following formula:
ROMI = ((income from marketing – cost of goods – marketing expenditures) / marketing expenditures) * 100.
If ROMI is less than 100%, then marketing investments were wasteful, if its more than 100%, they were profitable.
For example, we need to understand the effectiveness of a Google ads campaign. Monthly spending was $2,400, and the campaign generated sales of $31,200.Taking into account the cost of goods sold totals $24,960, the effectiveness of the advertising campaign is calculated with the formula:
ROMI = ((31,200 – 24,960 – 2,400) / 2,400) * 100 = 160%
In this case, the ROMI equals 160% for the Google ads campaign. This means that the campaign is profitable. The campaign, therefore, generated $1.60 of income for every dollar spent on marketing.

Return on ad spend (ROAS) is one of the most straightforward revenue-based metrics to measure. It is the total revenue generated for a specific marketing channel (like Google PPC) divided by the total spend on that channel.
ROAS is an indicator of return on investment in advertising. It is mostly similar to ROMI and is calculated using the following formula:
ROAS = income from marketing / marketing expenditures
Such a metric is very similar to the ROMI formula without deducting the cost of goods and advertising expenditures.
For example:
ROAS = 31,200 / 2,400 = 13
For each dollar spent, we gained $13, which at first glance seems like a lot, although from the return on marketing investment calculation, we know that ROMI is only 160%.