The Wayback Machine - https://web.archive.org/web/20160617165223/https://dev.twitter.com/ads/analytics/metrics-derived

Derived Metrics (version 0)

This guide refers to version 0, which is DEPRECATED and has been replaced with version 1.0 analytics. Version 0 endpoints will no longer be supported after June 30, 2016.

Campaign metrics depend on their campaign objective. Use this guide to determine how to calculcate derived metrics for use based on the objectives in place.

Any metric without curley brackets is one that is returned by the Ads API analytics endpoints. Any name surrounded by {curley brackets} indicates a derived metric for that category.

TWEET_ENGAGEMENTS

Derived MetricExposed Metric Calculation
{Impressions}promoted_tweet_search_impressions + promoted_tweet_timeline_impressions + promoted_tweet_profile_impressions
{CPM}billed_charge_local_micro / {Impressions} / 1000
{Total Engagements}promoted_account_follows + promoted_tweet_search_engagements + promoted_tweet_timeline_engagements + promoted_tweet_profile_engagements

or

promoted_account_follows + promoted_tweet_search_clicks + promoted_tweet_search_replies + promoted_tweet_search_retweets + promoted_tweet_search_follows + promoted_tweet_timeline_clicks + promoted_tweet_timeline_replies + promoted_tweet_timeline_retweets + promoted_tweet_timeline_follows + promoted_tweet_profile_clicks + promoted_tweet_profile_replies + promoted_tweet_profile_retweets + promoted_tweet_profile_follows
{Engagement Rate}{Total Engagements} / {Impressions}
{CPE}billed_charge_local_micro / {Total Engagements}
{Media Views}promoted_tweet_timeline_media_views + promoted_tweet_search_media_views + promoted_tweet_profile_media_views
{Media View Rate}{Media Views} / {Impressions}

WEBSITE_CLICKS

Derived MetricExposed Metric Calculation
{Impressions}promoted_tweet_search_impressions + promoted_tweet_timeline_impressions + promoted_tweet_profile_impressions
{CPM}billed_charge_local_micro / {Impressions} / 1000
{Link Clicks}promoted_tweet_search_url_clicks + promoted_tweet_timeline_url_clicks + promoted_tweet_profile_url_clicks
{Click Rate}{Link Clicks} / {Impressions}
{CPLC}billed_charge_local_micro / {Link Clicks}
{Conversion}conversion_custom + conversion_site_visits + conversion_sign_ups + conversion_downloads + conversion_purchases
{Conversion Rate}{Conversion} / {Impressions}
{CPA}billed_charge_local_micro / {Conversion}

APP_INSTALLS, APP_ENGAGEMENTS

Derived MetricExposed Metric Calculation
{Impressions}promoted_tweet_search_impressions + promoted_tweet_timeline_impressions
{CPM}billed_charge_local_micro / {Impressions} / 1000
{App Clicks}promoted_tweet_app_install_attempts + promoted_tweet_app_open_attempts + promoted_tweet_timeline_url_clicks + promoted_tweet_search_url_clicks
{App Click Rate}{App Clicks} / {Impressions}
{CPAC}billed_charge_local_micro / {App Clicks}
{CPI}billed_charge_local_micro / mobile_conversion_installs

FOLLOWERS

Derived MetricExposed Metric Calculation
{Impressions}promoted_account_impressions
{CPM}billed_charge_local_micro / {Impressions} / 1000
{Followers}promoted_account_follows + promoted_tweet_profile_follows
{Follow Rate}promoted_account_follow_rate
{CPF}billed_charge_local_micro / {Followers}
{Media Views}promoted_tweet_timeline_media_views + promoted_tweet_search_media_views + promoted_tweet_profile_media_views
{Media View Rate}{Media Views} / {Impressions}

LEAD_GENERATION

Derived MetricExposed Metric Calculation
{Impressions}promoted_tweet_search_impressions + promoted_tweet_timeline_impressions + promoted_tweet_profile_impressions
{CPM}billed_charge_local_micro / {Impressions} / 1000
{Leads}promoted_tweet_search_card_engagements + promoted_tweet_timeline_card_engagements + promoted_tweet_profile_card_engagements
{Lead Rate}{Leads} / {Impressions}
{Cost Per Lead}billed_charge_local_micro / {Leads}

VIDEO_VIEWS

Derived MetricExposed Metric Calculation
{Impressions}promoted_tweet_search_impressions + promoted_tweet_timeline_impressions + promoted_tweet_profile_impressions
{CPM}billed_charge_local_micro / {Impressions} / 1000
{Video Views}promoted_video_total_views
{Video Rate}promoted_video_total_views / {Impressions}
{Cost Per View}billed_charge_local_micro / promoted_video_total_views

QUALIFIED_IMPRESSIONS

Derived MetricExposed Metric Calculation
{Impressions}promoted_tweet_search_impressions + promoted_tweet_timeline_impressions + promoted_tweet_profile_impressions
{CPM}billed_charge_local_micro / {Impressions} / 1000
{Qualified Impressions}promoted_tweet_timeline_qualified_impressions + promoted_tweet_search_qualified_impressions + promoted_tweet_profile_qualified_impressions
{Qualified Impression Rate}{Qualified Impressions} / {Impressions}
{qCPM}billed_charge_local_micro / {Qualified Impressions} / 1000

CUSTOM

For product_type of PROMOTED_ACCOUNT see the FOLLOWERS objective above. For all other product types with this objective, see TWEET_ENGAGEMENTS for the corresponding derived metrics.