20 3 Points When testing a research hypothesis, ______ in measurement increases our chances of finding a statistically significant result. creativity precision certainty prediction Question 21 3 Points Many statistical techniques are based on the assumption that ______. a sampling frame was available convenience sampling was used sampling has been systematic sampling has been random Question 22 3 Points As indicated in the textbook, random sampling is ______ used and random assignment is ______ used. commonly; rarely rarely; commonly commonly; commonly rarely; rarely Question 23 3 Points Stratified sampling is used ______. only when simple random samples are inappropriate when systematic samples are not possible when you want to represent groups of different sizes as much as possible due to its superiority