In: Statistics and Probability
QUESTION 1:
For reasons known only to social scientists, the General Social Survey (GSS) regularly asks its subjects their astrological sign. Here are the counts of responses for the 2012 GSS:
Sign | Aries | Taurus | Gemini | Cancer | Leo | Virgo |
Count | 142 | 155 | 160 | 156 | 187 | 169 |
Sign | Libra | Scorpio | Sagittarius | Capricorn | Aquarius | Pisces |
Count | 188 | 152 | 155 | 142 | 166 | 150 |
If births are spread uniformly across the year, we expect all 12 signs to be equally likely. Are they? Use α=0.05α=0.05.
χ2(±0.0001)=χ2(±0.0001)=
P(±0.0001)=P(±0.0001)=
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QUESTION 2:
We suspect that people who rely entirely on cell phones will as a group be younger than those who have a landline telephone. Do data confirm this guess? The Pew Research Center interviewed separate random samples of cell-only and landline telephone users and broke down the samples by age group
LANDLINE SAMPLE | CELL-ONLY SAMPLE | |
Age 18-29 | 372 | 337 |
Age 30-49 | 337 | 1251 |
Age 50-64 | 141 | 1627 |
Age 65 or older | 30 | 1473 |
Total | 880 | 4688 |
(a) Should you use a chi-square test of independence or homogeneity:
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(b) Carry out a chi-square test. Test H0:H0: the distribution of age groups is the same for landline and cell-only individuals versus Ha:Ha: the distributions are different. Use α=0.01α=0.01.
χ2(±0.0001)=χ2(±0.0001)=
P(±0.0001)=P(±0.0001)=
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Categories | Observed | Expected | (fo-fe)2/fe |
Aries | 142 | 1922*0.08333=160.16 | (142-160.16)2/160.16 = 2.059 |
Taurus | 155 | 1922*0.08333=160.16 | (155-160.16)2/160.16 = 0.166 |
Gemini | 160 | 1922*0.08333=160.16 | (160-160.16)2/160.16 = 0 |
Cancer | 156 | 1922*0.08333=160.16 | (156-160.16)2/160.16 = 0.108 |
Leo | 187 | 1922*0.08333=160.16 | (187-160.16)2/160.16 = 4.498 |
Virgo | 169 | 1922*0.08333=160.16 | (169-160.16)2/160.16 = 0.488 |
Libra | 188 | 1922*0.08333=160.16 | (188-160.16)2/160.16 = 4.839 |
Scorpio | 152 | 1922*0.08333=160.16 | (152-160.16)2/160.16 = 0.416 |
Sagittarius | 155 | 1922*0.08333=160.16 | (155-160.16)2/160.16 = 0.166 |
Capricorn | 142 | 1922*0.08333=160.16 | (142-160.16)2/160.16 = 2.059 |
Aquarius | 166 | 1922*0.08333=160.16 | (166-160.16)2/160.16 = 0.213 |
Pisces | 150 | 1922*0.08333=160.16 | (150-160.16)2/160.16 = 0.645 |
Sum = | 1922 | 1922 | 15.657 |