FOUNDATIONS
This branch of statistics focuses on organizing, summarizing, and describing the essential features of a dataset without making generalizations beyond the observed data.
Descriptive Statistics
This refers to the complete set of individuals, objects, or events possessing the characteristics being studied.
Population
This refers to the number of participants needed in a research study to obtain reliable and valid results.
Sample Size
This measure of central tendency is obtained by adding all values and dividing by the number of observations.
Mean
This distribution has a bell-shaped and symmetric pattern in which the mean, median, and mode are equal.
Symmetrical / Normal Distribution
A researcher surveys 500 randomly selected Filipino college students and concludes that most college students in the Philippines prefer blended learning. Is this descriptive or inferential statistics?
Inferential Statistics
A university has 2,500 students. A researcher assigns every student a number and uses a random number generator to select 335 students. What sampling technique is being used?
Simple Random Sampling
If a researcher wants a smaller margin of error, should the required sample size generally increase or decrease?
Increase
A dataset contains several extremely high household incomes. Which measure of central tendency would generally be more appropriate because it is less affected by extreme values?
Median
A distribution has a long tail extending toward the right, with most observations concentrated on the lower end. What type of distribution is this?
Positively Skewed / Right-Skewed Distribution
A variable such as number of students in a classroom is quantitative. Because its values are countable, what specific type of quantitative variable is it?
Discrete Variable
A researcher selects a random starting student from a list and then selects every 20th student afterward. What sampling technique is this?
Systematic Random Sampling
A researcher wants to test whether two teaching strategies produce significantly different examination scores. Rather than simply estimating a population proportion, the researcher needs to determine a sample capable of detecting an effect. What approach is recommended?
Power Analysis
Two classes both have a mean examination score of 80. Class A's scores are between 78 and 82, while Class B's scores range from 60 to 100. Which class has the larger standard deviation?
Class B
In a positively skewed distribution, which relationship among the three measures is generally expected?
Mean > Median > Mode
A researcher records the temperature in degrees Celsius. The values have meaningful differences, but zero does not indicate the complete absence of temperature. What level of measurement is this?
Interval
A researcher wants to study students across four colleges. Because the colleges may have different experiences, students are randomly selected from each college. What sampling technique is most appropriate?
Stratified Random Sampling
In power analysis, this value represents the probability of correctly detecting a true effect when it actually exists. A commonly recommended value is 0.80.
Statistical Power
A dataset has a first quartile of 25 and a third quartile of 65. What is its interquartile range?
40
A dataset's graph has two distinct peaks, suggesting that the observations may come from two different groups or populations. What type of distribution is this?
Bimodal Distribution
A researcher wants to study students' satisfaction using the categories Very Dissatisfied, Dissatisfied, Neutral, Satisfied, and Very Satisfied. The categories have an order, but the differences between them cannot necessarily be assumed equal. What level of measurement is appropriate?
Ordinal
A nationwide educational study randomly selects regions → provinces → municipalities → schools → students. What sampling design combines several probability sampling techniques across successive stages?
Multistage Sampling
A researcher uses the same sample-size formula solely because the population contains 10,000 people, without considering the planned statistical test, effect size, power, or research objective. According to the lesson, what major mistake is being committed?
Relying solely on population size / ignoring the planned statistical analysis and other factors affecting sample size.
Two groups have these results:
Group A: Mean = 80, Median = 80
Group B: Mean = 80, Median = 70
Which group appears more stable, and why?
Group A, because its mean and median are equal, suggesting a more balanced/symmetric distribution with less indication of skewness.
A distribution has a long tail toward lower values. What type of skewness does it have?
Negative (left) skewness