The level of significance, represented by the Greek letter $\alpha$ (alpha), is a critical threshold in hypothesis testing. It defines the probability of rejecting the null hypothesis when it is, in fact, true.
This specific outcome—rejecting a true null hypothesis—is defined as a Type I error.
Consequently, the value of $\alpha$ directly corresponds to the probability of committing a Type I error. An increase in $\alpha$ means that the researcher is willing to accept a higher risk of incorrectly rejecting the null hypothesis.
For example, increasing $\alpha$ from 0.05 to 0.10 increases the probability of a Type I error from 5% to 10%.
Therefore, an increase in alpha directly leads to an increase in the probability of a Type I error occurring.