Equality (or "homogeneity") of variances, called homoscedasticity—the variance of data in groups should be the same.
iːkwˈɔlᵻɾi ɔːɹ "hˈɑːmoʊdʒnˌeɪɾi"ʌv vˈɛɹiənsᵻz, kˈɔːld hˌoʊmoʊsˌɛdɐstˈɪsᵻɾi—ðə vˈɛɹiəns ʌv dˈeɪɾə ɪn ɡɹˈuːps ʃˌʊd biː ðə sˈeɪm.