The GET /v1/stats/events end-point does not surface every statistics you can get from WonderPush, like the number of received notifications or viewed in-apps.
This end-point however exposes all the available statistics. It also exposes unique event counts, where you can get the number of notified users in a given time window instead of getting the total number of notifications sent.

There are a few metrics type available:

Delta integers (key int): They count increments, things that can be added together.
Unique counts (key card): They count how many unique things happened. The count is approximate and has a theoretical precision of 0.81%. Non unique counts are also tracked next to unique counts and accessible under the key dupCard.
Absolute integers (key int): They measure a value. These values cannot be added together. The last value measured in a time-window is remembered: the value of a day will be the same as the value of the last hour of the day.
Delta decimals (key flt): Just like Delta integers but with decimal values.

Available metrics:

Metric: events
Type: Delta integers
Params: None
Dimensions: type, subtype
Description: Counts the individual events by type, and subtype where applicable.
Metric: events.type
Type: Delta integers
Params: type (the event type), viewId (use an empty string for the full view)
Dimensions: subtype, platform, campaignId
Description: Detailed counts for a given events type in a given view, broken down by platform and campaignId.
Metric: eventInstallations.type
Type: Unique counts
Params: type (the event type), viewId (use an empty string for the full view)
Dimensions: subtype, platform, campaignId
Description: Like events.type but with unique counts.
Metric: campaign.events.type
Type: Delta integers
Params: type (the event type), campaignId
Dimensions: subtype, platform, campaignId
Description: Like events.type but for a given campaign.
Metric: campaign.eventInstallations.type
Type: Unique counts
Params: type (the event type), campaignId
Dimensions: subtype, platform, campaignId
Description: Like campaign.events.type but with unique counts.
Metric: notification.events.type
Type: Delta integers
Params: type (the event type), notificationId
Dimensions: subtype, platform, buttonLabel (the label of the clicked button, used for some event types)
Description: Like campaign.events.type but for a given notification. A new notification is used for each A/B test or for each API-triggered delivery.
Metric: notification.eventInstallations.type
Type: Unique counts
Params: type (the event type), campaignId
Dimensions: subtype, platform, buttonLabel (the label of the clicked button, used for some event types)
Description: Like notification.events.type but with unique counts.
Metric: segment.installations
Type: Absolute integers
Params: viewId (use an empty string for the full view), segmentId (note that only selected segments are available)
Dimensions: platform, reachability (whether the installation is optIn, softOptOut or optOut)
Description: A measure of the segment size at a given point in time.

Each request in the bulk will have a corresponding response under the bulkValues key.
One such response will have a list of groups containing one value per configured break down. If no dimension or time break down is used, there will be a single value inside the list. The sibling field dimensions lists the dimensions used for the breakdown, if any.
Each value in groups has a value key that gives you access to the desired value under a key corresponding to the metric type (see the description of metric types). Any broken down dimensions will have it's current value listed under dimensions. For example "dimensions": { "platform": "Android" } means that this group is about the Android platform. If the statistics are broken down by time, a date field will give the time of the begining of the time bucket this group is about.