result, items on the resulting scale, termed the K (for "correction") scale would be difficult to avoid for individuals attempting to present as well-adjusted when taking the MMPI. Individuals who endorsed the K scale items were thought to be demonstrating a sophisticated attempt to conceal information about their mental health history from test administrators. The K scale is an early example of a putative suppressor variable. The K scale is used as a complement validity indicator to the L (for "lie") scale, whose items were selected based on item content face validity and are more obviously focused on impression management. The K scale has been popular among clinical psychologists, and has been a useful tool for MMPI and MMPI-2 profile interpretation. Meehl and Hathaway continued to conduct research using MMPI validity indicators and noticed K scales elevations were associated with greater denial of symptoms on some clinical scales more than others. To compensate for this, they developed a K scale correction factor aimed at offsetting effects of defensive responding on other scales measuring psychopathology. Substantial subsequent research conducted on the original MMPI clinical scales used these "K-corrected" scores, although research on the usefulness of the corrections has produced mixed results. The most recent iteration of the K scale, developed for the MMPI-2-RF, is still used for psychological assessments in clinical, neuropsychological, and forensic contexts. Clinical versus statistical prediction Meehl's proposal Meehl's 1954 book Clinical vs. Statistical Prediction: A Theoretical Analysis and a Review of the Evidence analyzed the claim that mechanical (i.e., formal, algorithmic, actuarial) methods of data combination would outperform clinical (i.e., subjective, informal) methods to predict behavior. Meehl argued that mechanical methods of prediction, when used correctly, make more efficient and reliable decisions about patient prognosis and treatment. His conclusions were controversial and have long conflicted with the prevailing consensus about psychiatric decision-making. Historically, mental health professionals commonly make decisions based on their professional clinical judgment (i.e., combining clinical information "in their head" and arriving at a prediction about a patient). Meehl theorized that clinicians would make more mistakes than a mechanical prediction tool created to combine clinical data and arrive at predictions. Within his view, mechanical prediction approaches need not exclude any type of data from being combined and could incorporate coded clinical impressions. Once the clinical information is quantified, Meehl proposed mechanical approaches would make 100% reliable predictions for exactly the same data every time. Clinical