To succeed in a negligence action, a plaintiff must prove that: (1) the defendant owed him or her a legal duty to refrain from negligent activities; (2) the defendant breached that duty; (3) that said breach proximately caused injury to plaintiff; (4) actual loss or damages resulted therefrom. Splendorio v. Bilray Demolition Co., Inc., 682 A.2d 461, 466 (R.I. 1996). A plaintiff must establish that the defendant had a duty to act or refrain from acting and that there was a causal relation between the act or omission of the defendant and the injury to the plaintiff. Schenck v. Roger Williams General Hospital, 119 R.I. 510, 514, 382 A.2d 514, 516-17 (1977). In particular, a plaintiff must establish a standard of care as well as a defendant's deviation from that standard. Souza v. Chaset, 519 A.2d 1132, 1135 (R.I. 1987). Further, "expert testimony is required to establish deviation from the standard of care when the lack of care is not so evident as to be obvious to a lay person." Richardson v. Fuchs, 523 A.2d 445, 450 (R.I 1987). Generally, proximate cause may be established by showing that the harm to the plaintiff would not have occurred but for the defendant's negligence. Schenck, 119 R.I. at 514-515, 382 A.2d at 517. Moreover, such "causal connection between negligence and a plaintiff's injury must be established by competent evidence and may not be based on conjecture or speculation." McLaughlin v. Moura, 754 A.2d 95, 98 (R.I. 2000) (citing Skaling v. Aetna Insurance Co., 742 A.2d 282, 288 (R.I. 1999)). Absent such proof, a plaintiff's verdict would be based on conjecture and speculation, and in such situations a defendant would be entitled to a judgment as a matter of law. See Schenck, 119 R.I. at 515, 382 A.2d at 517. Furthermore, it is well-settled in Rhode Island that a plaintiff claiming injury that is due to tort "has a duty to exercise reasonable diligence and ordinary care in attempting to minimize his or her damages." Tomaino v. Concord Oil of Newport, Inc., 709 A.2d 1016, 1026 (R.I. 1998).