Statistics Technology & Digital Applications 2

Question 1

In R, which function is used to compute the Pearson correlation coefficient between two numeric vectors x and y?

Accepted Answer

cor(x, y)

Answer

The cor() function in R computes the Pearson correlation coefficient by default when given two numeric vectors.

Question 2

A data analyst runs a logistic regression in Python's scikit-learn and calls model.predict_proba(X). What does this return?

Accepted Answer

Probability estimates for each class

Answer

predict_proba() returns estimated class probabilities rather than hard class label predictions.

Question 3

Which SQL aggregate function computes the arithmetic mean of a numeric column named 'score'?

Accepted Answer

AVG(score)

Answer

AVG() is the standard SQL aggregate function that calculates the arithmetic mean of non-null values in a column.

Question 4

In a Jupyter Notebook, a statistician wants to display a histogram of variable 'data' using matplotlib. Which call is correct?

Accepted Answer

plt.hist(data)

Answer

plt.hist() generates a histogram, which displays the frequency distribution of a continuous variable.

Question 5

Which Excel function calculates the standard deviation of a population stored in cells A1:A20?

Accepted Answer

=STDEVP(A1:A20)

Answer

STDEVP() divides by N (population), while STDEV() divides by N-1 (sample), making STDEVP correct for a full population.

Statistics Practice Test