1. Chapter 6  PROBABILITY AND HYPOTHESIS TESTING
Understanding Statistics for International Social Work and Other Behavioral Sciences
Serge Lee, Maria C Silveira Nunes Dinis, Lois Lowe and Kelly Anders (2015). Oxford University Press

2. HYPOTHESIS TESTING
Hypothesis is a statement of an educational hunch or speculation about a presumed relationship in the real world
Two types of theses:
Research Hypothesis. Such hypothesis predicts how changes in one variable (independent) are proposed to cause or explain changes in another variable (dependent). For example, the average healthcare needs for people without health insurance are twice as much as those who have health insurance.
Null Hypothesis. Such hypothesis states that despite what the sample data suggests, after taking into account sampling errors or chance fluctuations, no real relationship or difference exits between the hypothesized statements. For example, children whose parents are supportive of them at school have the same level of self-esteem scores as children whose parents are not supportive.

3. DIRECTION OF THE HYPOTHESIS
When testing a hypothesis, one may use a directional or non-directional hypothesis
Directional (one-tailed) hypothesis is used to test hypotheses that researchers are certain of or able to predict the direction that the relationship will fall on the normal curve
Non-directional (two-tailed) hypothesis is used to test hypotheses where researchers believe that significant difference do exist but are unsure or unable to predict the direction of the relationship.

4. Probability of an event = x 100%
CONSTRUCTING THE CONFIDENCE INTERVAL
Chance is refers to as sampling error that can affect variation between or among variables in sample statistics
Probability is a mathematical equation that shows the proportion or fraction of times that a particular outcome will occur
Probability of an event = x 100%
Confidence interval, allows the researchers to construct an interval or range of scores around a point estimate, and allows the researchers to state a level of confidence in how likely it is that the interval contains the population parameters being estimated

5. FOUR POSSIBLE OUTCOMES ASSOCIATED WITH HYPOTHESIS TESTING
Determine whether to accept or reject the null hypothesis
Decision regarding the null hypothesis ()
The truth regarding the research hypothesis (
Reject
Fail to reject
is True
Correct decision
Type II error
is False
Type I error
Lee. Dinis, Lowe, Anders (2015). Understanding statistics for international social work and other behavioral sciences. Oxford University Press

6. ALTERNATIVE EXPLANATIONS
Use the following possible explanations to support findings when the research hypothesis cannot be explained
Rival hypothesis. Other variables that may cause a relationship to occur
Design flaws. Design flaws occur when the researchers are not careful with the measuring instruments and sampling bias
Sampling error. Sampling error usually occurs due to unequal sample size, small sample, and changes of data collection procedures