Inference for One Mean (program 21)

Sample standard deviation used in t-formulas
-William Gossett (student)

Comparison of normal and t-distributions

1. variation of the SD causes t to be wider

2. increasing sample-size reduces differences between distributions

3. degrees of freedom

National Institute of Standards and Technology

• determining and generating the certified values for the population of the materials
• making the population homogeneous (grinding, pulverizing, etc.)
• stratified sampling scheme
• using CIs to explore uncertainty

PCB levels in 10 vials of solution

• t-confidence interval and finding multiplier values

Paired comparison study

• Nutrasweet and maintaining a consistent taste
  • using paired t-test to see if Nutrasweet loses flavor over time
  • one-tailed test since only concerned if it loses sweetness
  • show steps to test and find critical value

Robustness of t-test:

• Problems with measuring social development (Vineland)
• -using paired t-test to compare social skills and daily living skills (CIs)

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