People gain weight when they take in more energy from food than they expend. Researchers wanted to investigate the link between obesity and energy spent on daily activity. Choose 20 healthy volunteers who don't exercise. Deliberately choose 10 who are lean and 10 who are mildly obese but still healthy. Attach sensors that monitor the subjects' every move for 10 days. The table below presents data on the time (in minutes per day) that the subjects spent standing or walking, sitting, and lying down. Is there a significant difference between the mean times the two groups spend lying down? Let ?1 be the mean time spent lying down by the lean group, and ?2 be the mean time for the obese group. Time (minutes per day) spent in three different postures by lean and obese subjects Group Subject Stand/Walk Sit Lie Lean 1 509.100 366.300 554.500 Lean 2 603.925 374.512 452.650 Lean 3 322.212 580.138 533.362 Lean 4 581.644 362.144 489.269 Lean 5 580.869 343.994 511.081 Lean 6 548.388 382.312 509.500 Lean 7 677.188 271.188 472.700 Lean 8 552.656 317.219 572.006 Lean 9 378.831 538.031 527.431 Lean 10 505.700 526.838 397.962 Obese 11 258.244 642.281 519.044 Obese 12 467.756 461.644 516.931 Obese 13 365.138 574.662 562.300 Obese 14 410.667 581.662 531.208 Obese 15 346.375 581.662 503.931 Obese 16 418.531 563.556 443.856 Obese 17 356.650 617.262 465.550 Obese 18 271.344 641.181 504.981 Obese 19 407.631 575.769 443.706 Obese 20 425.356 592.369 414.919 1) Find the size, mean and standard deviation of each group. n x s Lean Obese 2) Calculate the test statistic. t= 3) What is the practical question that requires a statistical test? Does the average time spent sitting differ from the average time spent lying down for lean and obese people? Do lean and obese people differ in the average time they spend lying down? Does the average time spent sitting or standing differ from the average time spent lying down for lean and obese people? Do lean and obese people differ in the average time they spend sitting
People gain weight when they take in more energy from food than they expend. Researchers wanted to investigate the link between obesity and energy spent on daily activity. Choose 20 healthy volunteers who don't exercise. Deliberately choose 10 who are lean and 10 who are mildly obese but still healthy. Attach sensors that monitor the subjects' every move for 10 days. The table below presents data on the time (in minutes per day) that the subjects spent standing or walking, sitting, and lying down. Is there a significant difference between the mean times the two groups spend lying down? Let ?1 be the mean time spent lying down by the lean group, and ?2 be the mean time for the obese group.
Time (minutes per day) spent in three different postures by lean and obese subjects |
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Group | Subject | Stand/Walk | Sit | Lie |
Lean | 1 | 509.100 | 366.300 | 554.500 |
Lean | 2 | 603.925 | 374.512 | 452.650 |
Lean | 3 | 322.212 | 580.138 | 533.362 |
Lean | 4 | 581.644 | 362.144 | 489.269 |
Lean | 5 | 580.869 | 343.994 | 511.081 |
Lean | 6 | 548.388 | 382.312 | 509.500 |
Lean | 7 | 677.188 | 271.188 | 472.700 |
Lean | 8 | 552.656 | 317.219 | 572.006 |
Lean | 9 | 378.831 | 538.031 | 527.431 |
Lean | 10 | 505.700 | 526.838 | 397.962 |
Obese | 11 | 258.244 | 642.281 | 519.044 |
Obese | 12 | 467.756 | 461.644 | 516.931 |
Obese | 13 | 365.138 | 574.662 | 562.300 |
Obese | 14 | 410.667 | 581.662 | 531.208 |
Obese | 15 | 346.375 | 581.662 | 503.931 |
Obese | 16 | 418.531 | 563.556 | 443.856 |
Obese | 17 | 356.650 | 617.262 | 465.550 |
Obese | 18 | 271.344 | 641.181 | 504.981 |
Obese | 19 | 407.631 | 575.769 | 443.706 |
Obese | 20 | 425.356 | 592.369 | 414.919 |
1) Find the size, mean and standard deviation of each group.
n |
x
|
s | |
---|---|---|---|
Lean | |||
Obese |
2) Calculate the test statistic. t=
3) What is the practical question that requires a statistical test?
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