ref: https://statistics.laerd.com/spss-tutorials/jonckheere-terpstra-test-using-spss-statistics.php

For k independent samples from a continuous field, this tests:

H0: F1(x)=F2(x)=...=FK(x); that is, the k samples are from populations with the same distribution function

HA: HA:F1(x)≥F2(x)≥...≥FK(x) or H´A:F1(x)≤F2(x)≤...≤FK(x) with at least one strict inequality.

p<α will reject the null hypothesis in favor of an ordered alternative (either direction of ordering).

ref: https://www.ibm.com/support/knowledgecenter/en/SSLVMB_21.0.0/com.ibm.spss.statistics.help/alg_nonparametric_independent_jonckheere-terpstra.htm