For example, determining that police officers are more likely to divorce than the general population, if that is not true, might result in marital problems being attributed to the fact that one person is a police officer rather than addressing underlying issues. I would set the significance level at .02 rather than at .05 to avoid having a Type I error, if my sample size was small enough for me to worry about the possibility of having a Type I error. However, with a sufficiently large population, I would keep my significance level at .05, because it is the standard for social science research.

M4Lab4

3. The null hypothesis is that there is no difference in the groups being examined for the variable in question. The directional research hypothesis is that there is a difference and suggests the nature of the difference (generally, that one population is more or less likely...

The nondirectional research hypothesis is that there is a difference between groups, but does not suggest the nature of the difference.
a. Attention span and out of seat classroom behavior

Null hypothesis: There is no difference between the out-of-seat behavior of children with normal attention spans and children with long attention spans.

Directional research hypothesis: Children with longer attention spans will exhibit better out-of-seat behavior than children with normal attention spans.

Nondirectional research hypothesis: There will be a difference in out-of-seat behavior between children with normal attention spans and children with long attention spans.

b.Relationship between marriage quality and the quality of a spouse's relationship with siblings

Null hypothesis: