Confidence Intervals (CI): Definition: A CI is a range of values that likely contains the true population parameter (e.g., mean) with a certain level of confidence (e.g., 95%). Interpretation: We can be 95% confident that the true population mean falls within the calculated interval. There's a 5% chance it falls outside. Width: The width of the CI depends on: Sample size: Larger samples lead to narrower CIs (more precise estimates). Variability (standard deviation): Less variable data (lower SD) results in narrower CIs. One-sided vs. Two-sided CI: A two-sided 95% CI has a 2.5% chance of error in each direction (upper and lower limits). A one-sided 95% CI can be derived from a two-sided 90% CI by focusing on only one direction (upper OR lower limit). This reduces the total error chance to 5%. Statements in Statistics: Statement 1: This refers to the conclusion drawn from the data, typically about a central tendency measure (mean, median) or other statistical summaries. Statement 2: