Making comparisons quantitative comparing means of two groups. Assessing soundness of the findings - reliability & validity. Reliability (a component of validity: any significant result must be more than a one-off finding; it must be repeatable or consistent. Set alpha level (p-value) level of probability of rejecting h0 when it is true. Control for a type i error: set p<0. 05. Establish an effect size the amount of difference between h0 and research findings. Determine power ( ) level of probability of accepting h0 when it is not true. Control for type ii error: set at 80% (to increase power, increase sample size). Set sample size set desired alpha level, effect size, and power then calculate sample size required. What kind of data are used: dependent or independent, continuous or categorical. How many groups are involved: one, two, or more than two.