Review - Unit 1: Descriptive and Inferential Statistics

1. What is the primary difference between an observational study and an experiment?

• a. Observational studies always involve larger sample sizes

•  b. Experiments manipulate variables, while observational studies do not

•  c. Observational studies are always more accurate than experiments

•  d. Experiments are always conducted in laboratories

2. Which of the following best describes the purpose of randomization in a study?

• a. To increase the sample size
  

•  b. To ensure all participants are identical

•  c. To reduce bias and create comparable groups

•  d. To eliminate the need for a control group

3. In the context of statistical studies, what is primary data?

•  a. Data collected directly by the researcher for the specific study

•  b. Data that is considered more important than other data

•  c. Information gathered from published sources

•  d. The first set of data collected in a longitudinal study

4. What is a key advantage of a sample survey over a complete census?

•  a. It always provides more accurate results

•  b. It requires more time and resources to conduct

•  c. It allows for the study of larger populations

•  d. It eliminates the need for statistical analysis

5. Which of the following statements about secondary data is correct?

•  a. It is always less reliable than primary data

•  b. It is data collected by someone other than the user

•  c. It can only be used for qualitative research

•  d. It is always more expensive to obtain than primary data

1. What does a z-score of 0 indicate about a data point?

• a. It is one standard deviation above the mean

•  b. It is equal to the mean

•  c. It is one standard deviation below the mean

•  d. It is two standard deviations above the mean

2. If a data point has a z-score of 2, what percentage of the data falls below it in a normal distribution?

•  a. Approximately 84%

•  b. Approximately 95%

•  c. Approximately 68%

•  d. Approximately 97.5%

3. Which formula correctly represents the calculation of a z-score?

4. In a dataset with a mean of 50 and a standard deviation of 10, what is the z-score for a value of 65?

•  0.5

• 2.5

•  1.0

• 1.5

What is the primary purpose of converting raw scores to z-scores?

• To increase the variability of the data

• To change the shape of the distribution

• To standardize units for comparison across different datasets

• To eliminate outliers from the dataset