Which of the following statistical methods requires two or more categorical variables?
Correct Answer:B
This is because a chi-squared test is a type of statistical method that tests the association or independence between two or more categorical variables, such as gender, race, or occupation. A chi-squared test can be used to compare the observed frequencies of the categories with the expected frequencies under the null hypothesis of no association or independence. For example, a chi-squared test can be used to determine if there is a relationship between smoking and lung cancer. The other statistical methods do not require two or more categorical variables. Here is why:
Simple linear regression is a type of statistical method that models the relationship between a continuous dependent variable and a continuous or categorical independent variable, such as height, weight, or education level. A simple linear regression can be used to estimate the slope and intercept of the best-fitting line that describes how the dependent variable changes with the independent variable. For example, a simple linear regression can be used to predict the weight of a person based on their height.
Z-test is a type of statistical method that tests the significance of the difference between a sample mean and a population mean, or between two sample means, when the population standard deviation or the sample sizes are large enough. A z-test can be used to compare the average scores of two groups of students on a standardized test.
Two-sample t-test is a type of statistical method that tests the significance of the difference between two sample means when the population standard deviation is unknown or the sample sizes are small. A two-sample t-test can be used to compare the average salaries of two groups of employees in different departments.
Which of the following is a domain-specific language used in programming that is designed for managing data that is held in a relational data stream management system?
Correct Answer:B
SQL (Structured Query Language) is a domain-specific language used in programming, specifically designed for managing data held in a relational database management system (RDBMS), or for stream processing in a relational data stream management system (RDSMS). It is the standard language for relational database management systems. SQL statements are used to perform tasks such as update data on a database, or retrieve data from a database. Unlike languages like Python or R, which are general-purpose programming languages, SQL is tailored specifically for database management and manipulation.
References:
✑ ResearchGate article on SQL1.
✑ SpringerLink chapter on Relational Databases and SQL Language2.
✑ DataCamp tutorial on SQL Server Installation3.
✑ Wikipedia page on SQL4.
Which of the following data sampling methods involves dividing a population into subgroups by similar characteristics?
Correct Answer:D
Stratified sampling is a data sampling method that involves dividing a population into subgroups by similar characteristics, such as age, gender, income, etc. Then, a simple random sample is drawn from each subgroup. This method ensures that each subgroup is adequately represented in the sample and reduces the sampling error. References: CompTIA Data+ Certification Exam Objectives, page 11.
A survey asks participants to rate a company on a scale of one to ten. Which of the following best describes the rating variable?
Correct Answer:B
The rating variable in a survey where participants rate a company on a scale of one to ten is best described as ordinal. This is because the ratings are ranked in order, with each number representing a position on a scale of satisfaction or quality. The numbers are not just labels (which would be nominal), nor do they represent a continuous spectrum (which would be continuous). They also do not fit the definition of categorical, as that implies non- ordered groups or categories. In an ordinal scale, the order of the values is significant and meaningful12.
References:
✑ Qualtrics explains that ordinal scales have answer sets that occur in a logical and systematic order, providing qualitative data.
✑ Zonka Feedback describes a 1 to 10 rating scale survey, indicating that the numbers represent a ranking from most negative to most positive experience, which aligns with the characteristics of an ordinal scale.
Which of the following is an example of a discrete variable?
Correct Answer:D
A discrete variable is a variable that can only take on a finite number of values, such as integers or categories. The number of people in an office is an example of a discrete variable, as it can only be a whole number. The temperature of a hot tub, the height of a horse, and the time to complete a task are examples of continuous variables, as they can take on any value within a range. Reference: CompTIA Data+ (DA0-001) Practice Certification Exams | Udemy