A hypothesis is, very simply, a guess one makes about what will happen. For example, if one were asked to predict which students would obtain higher achievement scores on a test, a group who used cooperative learning or a group who received lecture-only, most would guess--hypothesize--that the cooperative learning group would obtain the higher achievement scores.
In most research situations, a hypothesis represents an educated, an informed, guess. Often the hypothesis is based on theory or logic; sometimes it is based on prior experience or data. When formulating a hypothesis, there are characteristics that will make it reasonable and acceptable to most readers.
Characteristics of Hypotheses
Type of Hypotheses
Hypotheses may be either directional, non-directional, or null. The specific wording of the hypothesis will depend upon whether the independent variable in question is qualitative or quantitative. In general, if the independent variable is qualitative, the hypothesis refers to group differences. For example, there will be differences between boys and girls in reading achievement. If the independent variable is quantitative, the hypothesis is written in the format of relationships among variables rather than group differences. For example, reading achievement is related to verbal recall ability. Specific differences among directional, non-directional, and null hypotheses are presented below, but first it is necessary to explain the types of relationships one may find among quantitative variables.
When one wishes to express the nature of the relationship between two quantitative variables, there several possible variations on types of relationships. In most cases, at least in education and the social sciences, relationships among quantitative variables will follow either a positive, negative (inverse), or no relationship pattern. Others are possible (e.g., non-linear relationships).
A positive relationship exists when two variables covary together in a similar manner; that is, when increases in one variable are associated with increases in another variable. So, in simpler terms, when one variable goes up , the other variable also goes up . For example, people with high levels of intelligence are expected to have higher grades in school; those with higher levels of motivation complete more work; the more publications a professor has in a given year, the higher the merit pay for that year.
A negative relationship represents two variables that covary in opposite directions. Thus, when one variable increases , the other variable decreases ¯. A negative relationship is also referred to as an inverse relationship. Two examples of inverse relationships are: the greater one's belief in one's ability to learn, the lower one's anxiety about a course; the more associated one feels with school, the less likely one will drop out of school.
Below is a matrix that identifies the type of hypothesis by the type of independent variable. More detailed descriptions of each type follow the matrix.
Matrix of Hypotheses
(Assuming the dependent variable is quantitative.)
Type of Hypothesis
Type of Independent Variable
|Directional||Group differences exist; one group expected to perform better
than the other group(s).
Example: Group A will do better than group B.
|Either a positive or negative relation will exist.
Example: Higher scores on A are associated with higher scores on B.
Example: Higher scores on A are associated with lower scores on B.
|Non-directional||Group differences exist, but it is not clear which group will
Example: There will be a difference between groups A and B.
|Relation will exist, but it is not clear if it will be
positive or negative.
Example: Variable A is associated with variable B.
|Null||No difference expected; groups will do the same.
Example: There is no difference between groups A and B.
|No relation expected.
Example: Variable A is not associated with variable B.
A directional hypothesis indicates that one expects a group to over- or under-perform relative to other groups, or for there to be a positive or negative relationship among variables. To know when to refer to group differences or relationships among variables, it is necessary to know whether the independent variable is qualitative or quantitative. As noted above, if the independent variable is qualitative, the hypothesis is written in a manner that indicates one group's superior (or inferior) performance. If the independent variable is quantitative, reference in the hypothesis is to positive or negative relationships among variables.
To illustrate a directional hypothesis, the following indicates that one group will perform better in achievement that another. Note that the independent variable is qualitative.
Directional Hypothesis 1: Students exposed to cooperative learning will score higher on an achievement test that students exposed to lecture.
The following directional hypothesis indicates a positive relation among the variables. Note that the independent variable is quantitative.
Directional Hypothesis 2: Students with higher levels of intelligence will score higher on tests designed to measure mental abilities. (The higher the intelligence, the better the test score.)
The following directional hypothesis indicates a negative relation among the variables. Note that the independent variable is quantitative.
Directional Hypothesis 3: Students with higher levels of test anxiety will score lower on an achievement test. (So, as anxiety increases, performance decreases.)
For qualitative independent variables, a non-directional hypothesis indicates that groups will differ, but does not specify which groups will be superior or inferior. For quantitative independent variables, the non-directional hypothesis simply indicates that a relationship exists, but does not specifies the nature (positive or negative) of the relationship.
Non-directional Hypothesis 1: There will be a difference in achievement between students exposed to cooperative learning and students exposed to lecture.
Note that for non-directional hypotheses with qualitative independent variables, it is important to specify that one expects a difference among the groups. This manner of writing non-directional hypotheses with qualitative independent variables is preferred over simply stating that the variables are related. But for non-directional hypotheses with quantitative independent variables, indicating that an association or relationship is expected is acceptable, as illustrated below.
Non-Directional Hypothesis 2: There is a relation between a student's level of intelligence and his or her score on a test designed to measure mental abilities.
For null hypotheses, one simply indicates that there will be no difference (for qualitative independent variables) or that no relation exists (for quantitative independent variables).
Null Hypothesis 1: There will be a no difference in achievement between students exposed to cooperative learning and students exposed to lecture.
Null Hypothesis 2: The is no relationship between a student's level of intelligence and his or her score on a test designed to measure mental abilities.
Sometimes one may read of a research hypothesis. A research hypothesis is nothing more than what the researcher expects to find in his or her study. Also, one may occasionally see reference to a statistical hypothesis. A statistical hypothesis is simply a null hypothesis.
Practice Exercise #1 for Hypotheses
For each of the following hypotheses, determine the following:
Illustrated Example 1:
Hypothesis: Students who enter educational research with prior research experience will demonstrate greater achievement than students who enter educational research without research experience.
Illustrated Example 2:
Hypothesis: The more a student studies, the better that student will do on achievement tests.
Practice Hypotheses: Identify each component for the hypotheses that follow. Answers are provided below.
Practice Exercise Answers
1. Children taught by the vocabulary method will learn more than children taught by the experimental method.
2. The greater one's retention ability, the more ones learning from related prose will increase.
3. Given equal prior learning, corrective and non-corrective instruction are likely to produce different levels of achievement among fourth-grade students.
4. Programs offering stipends will be just as successful at retaining students as programs not offering stipends.
5. In a middle-class, suburban, public school district in which a child is expected to meet the standards of a set curriculum, a child who is under five years of age upon entrance to kindergarten is less likely to be ready for first grade in one year than a child who is five years of age or more at the time of entrance to kindergarten.
6. Fourth grade students who participate in computer assisted instruction (CAI) will have higher mathematics achievement scores than fourth grade students who do not participate in CAI.
7. Teachers who establish rapport with their students will be more effective in motivating students to study than teachers who do not establish rapport with their students.
8. Students with higher SAT scores will also have higher GRE scores; similarly, students with lower SAT scores will have lower GRE scores.
9. Under intangible reinforcement conditions, middle-class children will learn more than lower-class children.
10. The average achievement group and the low achievement group will show the same level in ratings of self-worth.
11. Classroom intellectual composition was expected to directly influence students academic achievement; the higher the classroom intellectual composition, the greater the academic achievement.
12. There will be no difference in mathematics achievement between the computer and tutor group, the computer-only group, and the traditional instruction group.
13. Students confidence in their academic ability, and their intelligence, are both related to achievement.
14. Test-taking experience affects test performance.
15. Students who receive individually guided instruction will demonstrate greater gains in reading achievement than students who receive group based instruction.
16. Students exposed to the read, visualize, and draw condition are expected to comprehend more of the biology text than are students in the read and visualize condition or the read only condition.
17. Science achievement is independent of academic self-efficacy.
18. One's perceptions of an effective teacher are in part determined by the perceivers attitudes toward education.
19. Academic performance in school is related to dropping out of school.
20. Perceived autonomy in the classroom predicts student evaluations of instruction.(Note. Perceived autonomy is measured by several responses to Likert scaled items. Reposes to each item range from 1 "strongly disagree" to 5 "strongly agree.")
Practice Exercise #2 for Hypotheses
Create one directional, one non-directional, and one null hypothesis for each set of variables listed below (thus a total of nine hypotheses). Be prepared to post your responses on-line during chats (for on-line course), or to read your responses in-class for regular classes.
Copyright © 1999, Bryan W. Griffin
Last revised on 06 January, 2005 03:19 PM