Distribution of the S_R statistic as defined in the text, for our V-band light curves. A dashed line denotes the threshold below which we searched for periodic variables. RR0, RR1, and RR01 variables are shown as red filled circles, green filled triangles, and blue open inverted triangles, respectively. SX Phe is indicated as open green triangles, the field Mira variable V27 (FI Hya) as a filled blue square, and the variable of unknown type V53 as an open green square. The three marked stars above the threshold are V40-V42, which we found to be non-variable.