Research & EBP Descriptive Statistics Review

What is validity in research?

• The consistency of a measure

• The accuracy of a measure in assessing what it intends to measure

• The average score of a dataset

• The spread of data around the mean

Answer explanation

Validity in research refers to the accuracy of a measure in assessing what it intends to measure. This ensures that the results truly reflect the concept being studied, making it the correct choice.

Which of the following best describes reliability?

• The ability to produce consistent results over time

• The ability to measure what it claims to measure

• The average of a dataset

• The difference between the highest and lowest scores

Answer explanation

Reliability refers to the ability to produce consistent results over time, ensuring that measurements remain stable across different instances. This distinguishes it from validity, which measures accuracy.

In a dataset, what does the mean represent?

• The most frequently occurring value

• The middle value when the data is arranged in order

• The average of all values

• The value that occurs least frequently

Answer explanation

The mean is calculated by adding all values in a dataset and dividing by the number of values, making it the average of all values. This distinguishes it from the mode (most frequent) and median (middle value).

If the following numbers represent a dataset: 5, 7, 9, 12, 12, 15, what is the mode?

• 7
  

• 12

• 9

• 15

Answer explanation

The mode is the number that appears most frequently in a dataset. In this case, the number 12 appears twice, while all other numbers appear only once. Therefore, the mode of the dataset is 12.

What is the median of the dataset: 3, 7, 8, 12, 14?

• 7
  

• 8

• 12

• 10

Answer explanation

To find the median, first arrange the dataset in order: 3, 7, 8, 12, 14. The median is the middle value. With five numbers, the median is the third number, which is 8.

What are descriptive statistics used for?

• To make predictions about a population
  
  

• To summarize and describe the characteristics of a dataset

• To assess the relationship between two variables

• To test hypotheses

Answer explanation

Descriptive statistics are used to summarize and describe the characteristics of a dataset, such as its central tendency and variability, making this the correct choice. Other options pertain to inferential statistics.

What does standard deviation measure?

• The average of a set of values

• The amount of variability or dispersion in a set of data

• The central tendency of a dataset

• The lowest value in a dataset

Answer explanation

Standard deviation quantifies the amount of variability or dispersion in a dataset, indicating how much individual data points differ from the mean. This makes it the correct choice over the other options.

The standard error of measurement (SEM) is used to indicate:

• The reliability of a measurement tool
  
  
  

• The average score of a sample

• The amount of error inherent in a measurement

• The mode of a dataset

Answer explanation

The standard error of measurement (SEM) quantifies the amount of error inherent in a measurement, indicating how much a score might vary due to measurement error. Thus, the correct choice is 'The amount of error inherent in a measurement'.

Which of the following situations may lower the validity of test?

• Mrs. Jose increases the number of items measuring each pupil skill from three to five

• Mr. Santos simplifies the language in the directions of the test.

• Miss Lopez removes the items in the achievement test that everyone would be able to answer correctly

• None of the above

Answer explanation

None of the situations listed would lower the validity of the test. Increasing item numbers, simplifying language, or removing easy items can enhance clarity and focus, thus maintaining or improving validity.

Adam has to find out if he should buy valentines for his coworkers. He asks the coworkers wearing a tie. Is this a valid sample?

• yes

• no

Answer explanation

No, this is not a valid sample because it only includes coworkers wearing ties, which may not represent the entire group. A better sample would include all coworkers to ensure diverse opinions.