Calpurnia is making the assumption that caesar does value his life and doesn't want to die. She is under the assumption that as his wife she will listen to him if she uses enough persuasion. She also assumes
that caesar is superstitious. It is necessary as a reader to understand that at the time of this play people were very superstitious, and the slightest thing would make them stay in all day to avoid the unknown possibility of death. It is clear that Calpurnia is very concerned with Caesars well being and does fear the possibility of him being hurt. She has the support of people telling him to beware the ides of march but fails to mention it, this, if used correctly could make her argument even stronger.
The support Calpurnia gives in this speech is strong. The support she used however would not hold up now and days. There was so much that was unknown back in those days that they had to just believe a lot of what they heard. Her using this to her advantage and making up things that if said in the modern era it would be dismissed and seen as implausible. As mentioned before she missed a big chunk of support that could have really helped her cause.
With the unique approach to the support and the various claims Calpurnia is very persuasive. Caesar is already set on leaving and doesn't want anyone to stop him, Calpurnia knew she had one chance. This works at first for Caesar but he is soon persuaded otherwise. The speech is set up well but with a few minor adjustments it could have completely stopped Caesar from leaving.