The first form for writing a quantitative hypothesis is the null hypothesis. The null hypothesis is denoted by H0, where H stands for hypothesis and the subscript zero implies a there is no difference condition, and H0 is read as “H sub zero”. The null hypothesis is a statement about the value of one or more unknown parameters – of a population- that is viewed to be true until sufficient evidence to the contrary. A researcher investigating the effect of two fertilizers on the yield of wheat would come up with a null hypothesis like; there is no significant difference between fertilizer A and fertilizer B on the yield of wheat. The alternative or directional hypothesis is the second form for writing a quantitative hypothesis.
This form is popular in journal articles. In an alternative or directional hypothesis, the researcher predicts an expected outcome of something. The basis of the researcher’s prediction is on literature and studies that project the prediction as a possible outcome. An example of an alternative or directional hypothesis is; Mathematics scores for this class will be higher than for the previous class. The non-directional hypothesis is the third form for writing a quantitative hypothesis, and in this form, the researcher’s prediction does not specify the exact form of difference (e.g., more, less).
The reason why the researcher does not specify the exact difference, as is the case in non-directional hypothesis, is that past materials or studies available to the researcher do not contain any predictions and so limit the researcher’s prediction. An example of a non-directional hypothesis would be the statement; individual members of communities living along water bodies with fish possess a high level of IQ owing to the high consumption of fish.