The impact of case factors on the initial screening decision in child welfare investigations in Norway

•Norwegian Child Welfare Services have a low threshold for investigating referrals with a great variation between agencies.•Almost half of all reported children had previously been reported and was known to the Child Welfare Services.•Analysis was performed by a multilevel logistic regression, which accounted for agency differences.•Severe, evident and specific concerns in the referral lowered the threshold for initiating investigation.•Previous registered referrals raised the threshold for investigation.