Formulate statistical questions that anticipate variability, distinguish categorical from numerical data and discrete from continuous data, and select appropriate data-collection methods, including a census, representative sample survey, observational study, or experiment. Calculate and interpret the mean, median, mode, and range for ungrouped data, select an appropriate measure of centre based on distribution and extreme values, and recognize biased survey wording and answer choices. Construct and interpret circle graphs using category frequencies, fractions, percentages, and central angles totaling $360^\circ$, and identify misleading scales, intervals, labels, units, boundaries, category choices, or visual dimensions in data displays.