In: Statistics and Probability
Complete the following chi square test:Show all work.
Example Chi Sq.
40% of Americans say that their favorite pastime is sports, 40% say that it’s time with their family, and 20% name something else. A survey of your neighborhood finds that 10 people report a preference for sports, 15 for being with their families, and 5 something else. Do your neighbors differ from Americans overall?
Activity Observed Expected EF O-E (O-E)2 (O-E)2/E
Sport 10 .4 12 -2 4 .33
Fam 15 .4 12 3 9 .75
Other 5 .2 6 -1 1 .17
30 2 = ∑ (O-E)2/E = 1.25
Is Paris, Chicago, or NY the most romantic city?
City Observed Expected EF O-E (O-E)2 (O-E)2/E
Chicago 2 .33
NY 40 .33
Paris 58 .33
100 2 = ∑ (O-E)2/E =
Is there a significant correlation between these two sets of numbers?
Weight Time
46 44
55 27
61 24
75 24
64 36
75 36
71 44
59 44
64 120
67 29
category | observed frequencey, O | expected proportion | expected frequency,E | (O-E)²/E | ||
sports | 10 | 0.400 | 12.00 | 0.333 | ||
family | 15 | 0.400 | 12.00 | 0.750 | ||
something else | 5 | 0.200 | 6.00 | 0.167 |
chi square test statistic,X² = Σ(O-E)²/E =
1.250
level of significance, α= 0.05
Degree of freedom=k-1= 3 -
1 = 2
P value = 0.5353 [ excel function:
=chisq.dist.rt(test-stat,df) ]
Decision: P value >α , Do not reject Ho
so, neighbors do not differ from Americans overall
................
category | observed frequencey, O | expected proportion | expected frequency,E | (O-E)²/E | ||
chicago | 2 | 0.333 | 33.33 | 29.453 | ||
NY | 40 | 0.333 | 33.33 | 1.333 | ||
PARIS | 58 | 0.333 | 33.33 | 18.253 |
chi square test statistic,X² = Σ(O-E)²/E =
49.040
level of significance, α= 0.05
Degree of freedom=k-1= 3 -
1 = 2
P value = 0.0000 [ excel function:
=chisq.dist.rt(test-stat,df) ]
Decision: P value < α, Reject Ho
...................
ΣX | ΣY | Σ(x-x̅)² | Σ(y-ȳ)² | Σ(x-x̅)(y-ȳ) | |
total sum | 637 | 428 | 738.1 | 7203.6 | -143.60 |
mean | 63.70 | 42.80 | SSxx | SSyy | SSxy |
correlation coefficient , r = Sxy/√(Sx.Sy)
= -0.0623
correlation hypothesis test
Ho: ρ = 0
Ha: ρ ╪ 0
n= 10
alpha,α = 0.05
correlation , r= -0.0623
t-test statistic = r*√(n-2)/√(1-r²) =
-0.176
DF=n-2 = 8
p-value = 0.8643
Decison: P value > α, So, Do not reject
Ho
SO, There is not any correlation
......................
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