Final answer:
The null hypothesis assumes no relationship between two variables and represents the assumption that observed effects are due to chance. It is often tested against an alternative hypothesis that suggests a significant relationship.
Step-by-step explanation:
The type of hypothesis that assumes no relationship between two variables is the null hypothesis. This hypothesis contains the assumption that any effect observed in a study is due to chance and that there are no underlying differences between groups or factors being investigated. The null hypothesis is typically represented by H0 (H-null) and is the starting point in hypothesis testing. It stands opposite to the alternative hypothesis, which proposes that there is a statistically significant relationship between variables.
In a hypothesis test, the goal is to determine whether to reject the null hypothesis in favor of the alternative hypothesis, based on the evidence provided by data. In scientific research, proposing multiple hypotheses can be useful when looking for explanations. For example, if a classroom is warm, one may hypothesize, "The classroom is warm because no one turned on the air conditioning." However, there may be alternative explanations such as a power failure preventing the air conditioning from working.