Various claims are often made for surveys. Why is each of the following claims not correct? a) It is always better to take a census than to draw a sample. b) Stopping students on their way out of the cafeteria is a good way to sample if we want to know about the quality of the food there. c) We drew a sample of 100 from the 3000 students in a school. To get the same level of precision for a town of 30,000 residents, well need a sample of 1000. d) A poll taken at a statistics support website garnered 12,357 responses. The majority said they enjoy doing statistics homework. With a sample size that large, we can be pretty sure that most Statistics students feel this way, too. e) The true percentage of all Statistics students who enjoy the homework is called a population statistic.

Chapter 14 Scatterplot: Relationship between 2 quantitative variable measured by the same individual. X axis: explanatory variable/ independent variable (Think I the scientist can control) Y axis: response variable/ dependent Example: The growth of a plant (inches) and the amount of sunlight given (seconds). Seconds of sunlight is the Independent variable ( something that can be controlled) Inches the plant grows would be the Dependent variable ( depends on the amount of light given) Sunlight (seconds) should be on the x axis Interpreting Scatterplots Look at overall pattern Look for outliers Described by form, direction and strength Form: clustered, curved, linear Strength: How close points follow the form