who developed an effective method for measuring attachment
Attachment measures The Strange Situation procedure was formulated to observe attachment relationships between a caregiver and children between the age of nine and 18 months. It was developed by Mary Ainsworth, a developmental psychologist[3] Originally it was devised to enable children to be classified into the attachment styles known as secure, anxious-avoidant and anxious-ambivalent. As research accumulated and atypical patterns of attachment became more apparent it was further developed by Main and Solomon in 1986 and 1990 to include the new category of disorganized/disoriented attachment.[4][5]
Micrometer The accuracy of micrometers is checked by using them to measure gauge blocks,[16] rods, or similar standards whose lengths are precisely and accurately known. If the gauge block is known to be 0.7500" ± .00005" ("seven-fifty plus or minus fifty millionths", that is, "seven hundred fifty thou plus or minus half a tenth"), then the micrometer should measure it as 0.7500". If the micrometer measures 0.7503", then it is out of calibration. Cleanliness and low (but consistent) torque are especially important when calibrating—each tenth (that is, ten-thousandth of an inch), or hundredth of a millimeter, "counts"; each is important. A mere spec of dirt, or a mere bit too much squeeze, obscure the truth of whether the instrument is able to read correctly. The solution is simply conscientiousness—cleaning, patience, due care and attention, and repeated measurements (good repeatability assures the calibrator that his/her technique is working correctly).