CompTIA Data+ (DA0-001) — All Questions

A report summarizes what happened last quarter, showing total sales, average order value, and month-over-month change. Which type of analytics is this?

• a.Descriptive analytics✓
• b.Predictive analytics
• c.Prescriptive analytics
• d.Diagnostic analytics

Descriptive analytics summarizes what has already happened using measures such as totals and averages. Diagnostic analytics explains why it happened, predictive forecasts what will happen, and prescriptive recommends what action to take.

An analyst observes that ice cream sales and drowning incidents both rise in the same months, but concludes that neither causes the other. Which statistical caution does this illustrate?

• a.A larger sample always guarantees causation
• b.Correlation does not imply causation✓
• c.The mean is always equal to the median
• d.Outliers can never affect an average

Two variables can move together because both are influenced by a third factor, here warm weather, so correlation does not by itself prove that one causes the other. Establishing causation requires additional evidence such as controlled experiments.

A dataset of household incomes contains a few extremely high values that pull the average upward. Which measure of central tendency is least affected by these extreme values and better represents the typical household?

• a.The mean
• b.The range
• c.The sum
• d.The median✓

The median is the middle value and is resistant to extreme outliers, so it better represents a typical value in a skewed distribution. The mean is pulled toward extreme values, while the range and sum are not measures of central tendency.

In hypothesis testing, an analyst obtains a p-value of 0.02 with a significance level (alpha) set at 0.05. What is the appropriate conclusion?

• a.Accept the null hypothesis as definitely true
• b.The result is inconclusive and no decision can be made
• c.Reject the null hypothesis because the p-value is below alpha✓
• d.Increase alpha to 0.50 to be safe

When the p-value is less than the chosen significance level, the result is statistically significant and the null hypothesis is rejected in favor of the alternative. A p-value of 0.02 is below 0.05, so the analyst rejects the null; testing never proves the null definitively true.

Which statistic best describes how spread out a set of values is around their mean?

• a.Standard deviation✓
• b.Mode
• c.Count
• d.Median

Standard deviation measures the dispersion of values around the mean, with larger values indicating greater spread. The mode is the most frequent value, count is the number of observations, and the median is the middle value, none of which quantify spread.