Thirty volunteers each ran 1 km in shoe A and later ran 1 km in shoe B; both times were recorded for every volunteer. Is this paired or two independent samples?

A clinic recorded blood pressure change for 42 adults taking drug A and 38 different adults taking drug B, with no adult in both groups. Is this paired or two independent samples?

On each of 20 fields, a farmer used fertilizer A on one half and fertilizer B on the other half, then measured yield in kilograms for both halves. Is this paired or two independent samples?

A counselor surveyed 60 juniors and 55 seniors, with no student in both grades, and recorded minutes of homework per night. Is this paired or two independent samples?

Eighteen cars were driven on the same route once in regular mode and once in eco mode, and fuel use in liters was recorded both times for each car. Is this paired or two independent samples?

A factory measured the diameter in millimeters of 25 bolts from machine A and 25 different bolts from machine B. Is this paired or two independent samples?

A sleep study recorded reaction time for 34 employees before a caffeine-free week and again after the week. Is this paired or two independent samples?

A hospital assigned 46 patients to physical therapy and 44 different patients to standard care, then recorded days until walking without help. Is this paired or two independent samples?

A tutor recorded test scores for 28 students before tutoring and after four tutoring sessions. Is this paired or two independent samples?

Fifty users rated an old app design and then rated a redesigned version; both ratings were recorded for every user. Is this paired or two independent samples?

A researcher measured resting pulse for 35 runners and 40 cyclists, with no athlete in both groups, and wants to compare mean pulse. Should the analysis use paired t, two-sample t, or one-sample t?

A utility study measured electricity use in 22 homes before insulation and after insulation. Should the analysis use paired t, two-sample t, or one-sample t?

Sixteen students solved a puzzle with a calculator and without a calculator, and each completion time in seconds was recorded. Should the analysis use paired t, two-sample t, or one-sample t?

A bottling plant sampled 48 bottles from line A and 52 different bottles from line B, then measured fill volume in milliliters. Should the analysis use paired t, two-sample t, or one-sample t?

A school recorded commute times for 30 ninth graders and 30 twelfth graders, with no student in both groups. Should the analysis use paired t, two-sample t, or one-sample t?

Twenty-four athletes were measured for vertical jump height before a training plan and again after the plan. Should the analysis use paired t, two-sample t, or one-sample t?

A teacher recorded each of 25 students' scores before and after a workshop, then analyzed the before scores and after scores as two independent samples. What is wrong?

In a nutrition study of 18 twin pairs, one twin used diet A and the other used diet B; an analyst treated the 18 A results and 18 B results as unrelated samples. What is wrong?

A lab measured mass loss for 40 tablets from shift A and 40 different tablets from shift B, then subtracted results by row order and used a paired t procedure. What is wrong?

Thirty-two patients rated pain after a drug and after a placebo in random order, but the analyst used a two-sample t procedure as if the groups were separate. What is wrong?

A vineyard treated one half of each of 18 plots and left the other half untreated, then measured grape yield in kilograms for both halves. What quantity should the paired analysis average?

Thirty students took a diagnostic test before a review course and a final test after it. What quantity should the paired analysis average?

Forty-two dogs were randomly assigned to food A or food B, 21 dogs per food, and weight gain in kilograms was recorded once for each dog. What quantities should the two-sample analysis compare?

Fourteen teachers each taught two matched class sections, one with new software and one without, and each section's mean test score was recorded. What quantity should the paired analysis average?