What is a population?
All individuals you want to study.
What is a sample?
A subset of the population used to make inferences.
What is voluntary response bias?
Bias that occurs when only people who choose to respond are included.
What is self-selection bias?
Bias caused when respondents decide themselves whether to participate.
What is funding bias?
Bias that occurs when research is funded by someone with an interest in the outcome.
What does “correlation does not imply causation” mean?
Just because two variables are related does not mean one causes the other.
What is a loaded question?
A question worded to influence or encourage a certain response.
What are misleading graphs?
Graphs that distort data using scale, labels, or visuals.
Why is adding percentages across groups a misuse of statistics?
Percentages must be based on the same whole to be combined correctly.
What is statistical significance?
Results that are unlikely to have occurred by chance.
What is practical significance?
Results that are large enough to matter in real life.
Example of statistical but not practical significance
A weight-loss program shows a statistically significant 1-lb loss, but it doesn’t matter in real life.
What is quantitative data?
Numeric data where calculations like mean and differences make sense.
What is discrete data?
Countable values (e.g., number of students).
What is continuous data?
Measurable values (e.g., height, weight, temperature).
What is qualitative (categorical) data?
Data that describes labels or categories.
What is the nominal level of measurement?
Qualitative data with no order (e.g., hair color).
What is the ordinal level of measurement?
Qualitative data with order but no meaningful differences (e.g., race placements).
What is the interval level of measurement?
Quantitative data with an arbitrary zero (e.g., temperature in °F or °C).
What is the ratio level of measurement?
Quantitative data with a true zero meaning none (e.g., weight, distance, money).
How do you remember interval vs. ratio?
Ratio = real zero; Interval = arbitrary zero.
What is an observational study?
Researchers observe without applying any treatment.
What is an experiment?
Researchers apply a treatment and measure the results.
What is a placebo?
A fake treatment used for comparison.
