Table 2 Explanation of crafted feature

Priority level set by EMCC

The priority level set by EMCC is presumed to affect response time due to the assessed urgency. Since all missions in all priority levels affect response time between priority levels, stratification between priority levels is not suitable. Instead, the priority level is handled as a feature affecting response time like the other variables investigated in this study.

Response time

A created feature using the time difference between when the EMCC call was received, and the first EMS resource arrival at scene of incident. The response time is a result of call handling time and travel time.

Call Handling time

A created feature using the time difference between when the EMCC call was received, and the first EMS resource received a mission from EMCC in the incident.

Travel time

A created feature using the time difference between when the first EMS resource received a mission from EMCC in the incident, and the first EMS resource arrival at scene of incident.

Reason of Call to EMCC

The reason of call to EMCC was grouped from the origin of 333 different categories, which differs slightly between different years, into 54 different categories reflecting the reason of call to EMCC. Reason of Call to EMCC is presumed to effect call handling time because differences in call handling time due to the nature of different reason of call to EMCC-categories. Reason of Call to EMCC is presumed to effect travel time because differences in travel time in different reason of call to EMCC-categories where personal EMS-personnel experience might influence travel time.

Locality

The locality was grouped from the origin of 115 localities, where the same localities was duplicated one ore several times due to misspelling, into 48 localities which reflect the real locality. Locality is presumed to affect call handling time due to amount of available resources might differ in different localities. If there is lack of resources in a locality the call handling time might increase due to finding nearest suitable resource. Locality is presumed to affect travel distance and travel time because different coverage of available resources in different localities. Differences related to locality might indicate EMS allocation out of tune.

Hour

The hour of day is used to investigate differences in response time between hour of day. Differences related to hour might indicate EMS allocation out of tune.

Month

The month of year is used to investigate differences between month of year. Differences related to month might indicate EMS allocation out of tune.

Year

The year is used to identify differences in years like the Covid-19 pandemic and differences in EMS allocation between years. Differences between years might indicate EMS allocation out of tune.

On scene time

A created feature using the time difference between when the first EMS resource arrival at scene of incident and the first EMS resource started transportation of patient.

Transportation time

A created feature using the time difference between when the first EMS resource started transportation of patient and the first EMS resource arrival at hospital.

Air temperature

The average temperature current day at the weather station called “Observatoriekullen” in the centre of Stockholm. Differences in temperature is presumed to affect response time in different ways, like low temperature in combination with precipitation could affect traffic and travel time. It could also generate differences in reason of call to EMCC related to high and low temperatures.

Airtemperature_max

The max temperature current day at the weather station called “Observatoriekullen” in the centre of Stockholm. Differences in max temperature is presumed to affect response time in different ways, like low temperature in combination with precipitation could affect traffic and travel time. It could also generate differences in reason of call to EMCC related to high and low temperatures.

Airtemperature_min

The min temperature current day at the weather station called “Observatoriekullen” in the centre of Stockholm. Differences in min temperature is presumed to affect response time in different ways, like low temperature in combination with precipitation could affect traffic and travel time. It could also generate differences in reason of call to EMCC related to high and low temperatures.

H_AVG_of_Responsetime

A created feature aggregating the response time as average response time of all missions current hour. The purpose is to reflect how the general response time the current hour effects response time in individual missions. Differences in the hourly average response time is presumed to reflect the system where increased hourly response time might indicate strained situation or EMS allocation out of tune.

H_AVG_of_Call_Handlingtime

A created feature aggregating the call handling time as average response time of all missions current hour. The purpose is to reflect how the general call handling time the current hour effects response time in individual missions. Differences in the hourly average call handling time is presumed to reflect the system where increased hourly call handling time might indicate strained situation or EMS allocation out of tune.

H_AVG_of_DistArrival_km

A created feature aggregating the travel distance to patient in all missions current hour. The purpose is to reflect how the general travel distance to patient the current hour effects response time in individual missions. Differences in the hourly average travel distance is presumed to reflect the system where increased travel distance might indicate strained situation or EMS allocation out of tune.

H_AVG_of_Drivetime

A created feature aggregating the drive time as average drive time of all missions current hour. The purpose is to reflect how the general drive time the current hour effects response time in individual missions. Differences in the drive time is presumed to reflect the system where increased travel distance might indicate strained situation or EMS allocation out of tune. The traffic situation is a factor highly affecting drive time.

H_AVG_of_Onscenetime

A created feature aggregating the on scene time as average on scene time of all missions current hour. The purpose is to reflect how the general on scene time the current hour effects response time in individual missions. Differences in the on scene time is presumed to indicate prolonged treatment time affecting the response time.

H_AVG_of_Transportationtime

A created feature aggregating the on transportation time as average transportation time of all missions current hour. The purpose is to reflect how the general transportation time the current hour effects response time in individual missions. Differences in the on scene time is presumed to indicate prolonged transportation time affecting the response time.

H_SumOfTasks

A created feature aggregating the sum of missions current hour. The purpose is to reflect how the sum of missions the current hour effects response time in individual missions. Differences in the sum of missions is presumed in relation to available resources is presumed affecting the response time.

H_Sum_of_MissionCancelled

A created feature aggregating the sum of cancelled missions the current hour. The purpose is to reflect how the sum of cancelled missions the current hour effects response time in individual missions. Differences in the sum of cancelled missions is presumed to reflect the system, where a strained situation with lack of resources, or EMS allocation out of tune, would give a higher rate of cancelled missions and affect the response time.

H_C_DIST_of_rakelid

A created feature aggregating the sum of distinct EMS resource ID the current hour. The purpose of this variable is to reflect how the sum of EMS resources assigned to a mission the current hour effects response time in individual missions. Differences in the sum of EMS resources in relation to the sum of missions affects response time.