The effect size is 1.6 sigma; 80 people, 40 in each group, 24 versus 14 improvements. The null hypothesis is by no means ruled out. That's in addition to the double-blinding problems others have noted.

It can work, but it's not an at-will magic spell, unfortunately. And it seems you gotta be a special kind of wizard to use the effect. If anyone knows how to reliably manifest I'll gladly apprentice under them. There's nothing that makes me think people who think hereustics and biases is a useful paradigm more than the existence of placebos. Magical thinking, while a 'bias', literally works and is useful. Anticipation is itself an effective mental magic trick. Here's a summary of the most evidence I've found:

"]) Roughly only 30% of the population seems susceptible to placebo effects, and it is not possible to determine ahead of time whether a placebo will work or not. (However the placebo effect is zero in studies of blood poisoning and up to 80% in studies of wound on the duodenum). Patients rightfully want immediate relief or improvement from their illness or symptoms. A non-placebo can often provide that, while a placebo might not. Legitimate doctors and pharmacists could open themselves up to charges of fraud since sugar pills would cost pennies or cents for a bottle, but the price for a “real” medication would have to be charged to avoid making the patient suspicious. - Google Search

The desire for relief from pain, “goal motivation”, and how far pain is expected to be relieved increases placebo analgesia.[82] Another factor increasing the effectiveness of placebos is the degree to which a person attends to their symptoms, “somatic focus”.[83] Individual variation in response to analgesic placebos has been linked to regional neurochemical differences in the internal affective state of the individuals experiencing pain.[140]Those with Alzheimer’s disease lose the capacity to be influenced by placebos, and this is attributed to the loss of their prefrontal cortex dependent capacity to have expectations.[141] - Google Search

Mechanism of the effectA 2001 meta-analysis of clinical trials with placebo groups and no-treatment groups found no evidence for a placebo effect on objectively measured outcomes and possible small benefits in studies with continuous subjective outcomes (particularly pain).[16] A 2004 follow-up analysis found similar results and increased evidence of bias in smaller trials that calls into question the apparent placebo effect on subjective outcomes.[42]Because the placebo response is simply the patient response that cannot be attributed to an investigational intervention, there are multiple possible components of a measured placebo effect. These components have varying relevance depending on study design and the types of observations.[43] While there is some evidence that placebo interventions can alter levels of hormones[44] or endogenous opioids,[45] other prominent components include expectancy effects, regression to the mean,[46][47] and flawed research methodologies. - Google Search

Since the publication of Henry K. Beecher’s The Powerful Placebo[15] in 1955, the phenomenon has been considered to have clinically important effects.[16] This view was notably challenged when, in 2001, a systematic review of clinical trials concluded that there was no evidence of clinically important effects, except perhaps in the treatment of pain and continuous subjective outcomes.[16] The article received a flurry of criticism,[17] but the authors later published a Cochrane review with similar conclusions (updated as of 2010).[18] Most studies have attributed the difference from baseline until the end of the trial to a placebo effect, but the reviewers examined studies which had both placebo and untreated groups in order to distinguish the placebo effect from the natural progression of the disease.[16] - Google Search

Motivation may contribute to the placebo effect. The active goals of an individual changes his/her somatic experience by altering the detection and interpretation of expectation-congruent symptoms, and by changing the behavioral strategies a person pursues.[82][83] Motivation may link to the meaning through which people experience illness and treatment. Such meaning is derived from the culture in which they live and which informs them about the nature of illness and how it responds to treatment. Research into the placebo treatment of gastric and duodenal ulcers shows that this varies widely with society.[17] The placebo effect in treating gastric ulcers is low in Brazil, higher in northern Europe (Denmark, Netherlands), and extremely high in Germany. However, the placebo effect in treating hypertension is lower in Germany than elsewhere.[84] Social observation can induce a placebo effect such when a person sees another having reduced pain following what they believe is a pain reducing procedure.[85] - Google Search