Test metrics accomplish in analyzing the current level of maturity in testing and give a projection on how to go about testing activities by allowing us to set goals and predict future trends. 

Many a times some test cases are skipped or omitted due to the following:

Ambiguity – Requirements with potential multiple meanings.
Completeness – Items left to be specified.
Understandability – The readability of the document.
Volatility – The rate and time within the life cycle changes are made to the requirements.
Traceability – The traceability of the requirements upward to higher level
documents and downward to code and tests.

Thus Normal Test Related Metrics are:
Quantity of tests Prepared / Performed Quantity of Defects found
Type of Defects found
Time taken – To Plan, Develop and Time taken – To Plan, Develop and Execute tests
Cost of defect management: bug Reporting, fixing and re-testing reporting, fixing and re- testing

Thus the Test team activity metrics are for: how long to Plan stage or phase of testing
Write the Test systems Design
Prepare Test environment and develop utilities.
Prepare test scenarios, scripts, data and expected results
Write automated test scripts
Execute tests for each significant stage of testing.
Raise Defect reports and manage issues
Retest fixed defects.

Example of Base Metrics:
# Test Cases
# New Test Cases
# Test Cases Executed
# Test Cases Unexecuted
# Test Cases Re-executed
# Passes
# Fails
# Test Cases Under Investigation
# Test Cases Blocked
# 1st Run Fails
Test Case Execution Time
# Testers
Example of Derived Metrics:
% Test Cases Complete
% Test Cases Passed
% Test Cases Failed
% Test Cases Blocked
% Test Defects Corrected 
 Let me know in xase any other details needs to be added.