Statistics Technology & Digital Applications 4

Question 1

Which Python pandas method removes rows with any missing values from a DataFrame named df?

Accepted Answer

df.dropna()

Answer

df.dropna() returns a new DataFrame with rows containing any NaN values removed by default.

Question 2

In R, the function lm(y ~ x, data=df) fits a linear model. Which function extracts the model's R-squared value from the result object?

Accepted Answer

summary()$r.squared

Answer

summary() on an lm object returns a list, and the $r.squared element specifically extracts the coefficient of determination.

Question 3

A data analyst exports a statistical report to a CSV file. Which delimiter character defines a CSV (Comma-Separated Values) file?

Accepted Answer

Comma

Answer

CSV files use commas as the field delimiter by default, though regional variants sometimes use semicolons.

Question 4

In Google Sheets, which function calculates the p-value for a two-tailed t-test between two data ranges A1:A30 and B1:B30?

Accepted Answer

=TTEST(A1:A30,B1:B30,2,2)

Answer

TTEST() with tails=2 and type=2 (two-tailed, two-sample equal variance) returns the p-value for comparing two independent groups.

Question 5

A machine learning pipeline uses scikit-learn's train_test_split(). Setting random_state=42 ensures what?

Accepted Answer

The same split is reproduced every run

Answer

random_state seeds the random number generator so the same training/test split is produced each time the code is run.

Statistics Practice Test