Statistics Class 12 Chapter 15 - Association - Solved MCQs for All Exam Boards

"THE HOLY QURAN AND STATISTICS"
Surah Al-Jinn (72:28):
وَأَحْصَىٰ كُلَّ شَيْءٍ عَدَدًا

"And He has enumerated everything in numbers." (Allah perfectly counts and knows the exact measure of all creations).

(F.Sc. Part – 2, Chapter 15: Association)

Q1. A characteristic which varies in quality:

A. Attribute

B. Qualitative variable

C. Quantitative variable

D. a and b   ✓ Correct Answer

Explanation: A characteristic that varies in quality (not measured numerically) is called both an attribute and a qualitative variable.

Q2. It is obtained by noting presence or absence in the objects:

A. Attribute

B. Qualitative variable

C. Quantitative variable

D. a and b   ✓ Correct Answer

Explanation: Noting the presence or absence of a characteristic defines an attribute, which is itself a type of qualitative variable.

Q3. The eye color of 100 men is:

A. Quantitative variable

B. Qualitative variable

C. Attribute

D. b and c   ✓ Correct Answer

Explanation: Eye color is a non-numeric characteristic, making it both a qualitative variable and an attribute.

Q4. A set of the objects which are sharing a given characteristic is:

A. Class   ✓ Correct Answer

B. Frequency

C. Total number of observation

D. None

Explanation: A group of objects sharing a common characteristic is called a class.

Q5. The number of observations which are distributed in a class is called:

A. Class

B. Frequency   ✓ Correct Answer

C. Total number of observation

D. None

Explanation: The count of observations falling within a class is called its frequency.

Q6. Classes represented by both positive and negative attributes are called:

A. Positive classes

B. Negative classes

C. Contrary class   ✓ Correct Answer

D. None

Explanation: A class defined by a mix of positive and negative attributes (e.g. Aβ) is called a contrary class.

Q7. The process of dividing the objects into two mutually exclusive classes is called:

A. Two way classification

B. Dichotomy

C. Four way classification

D. a and b   ✓ Correct Answer

Explanation: Splitting objects into two mutually exclusive classes is called both two-way classification and dichotomy.

Q8. Classes specified by two attributes are known as the classes of order:

A. 0

B. 1

C. 2   ✓ Correct Answer

D. 3

Explanation: When classes are specified using two attributes together, they are classes of order 2.

Q9. For k attributes the total number of class frequencies would be:

A. 2ᵏ   ✓ Correct Answer

B. 1ᵏ

C. 4ᵏ

D. 3ᵏ

Explanation: For k attributes, the total number of class frequencies (of all orders combined) is 2ᵏ.

Q10. In study of attributes the frequencies of classes of the highest order are called:

A. Ultimate frequencies   ✓ Correct Answer

B. Simple frequencies

C. Marginal frequencies

D. None

Explanation: The frequencies of the highest-order classes (specified by all attributes) are called ultimate frequencies.

Q11. In study of attributes the total number of observations 'n' is the frequency of the class of order:

A. 0   ✓ Correct Answer

B. 1

C. 2

D. 3

Explanation: The total number of observations 'n' represents the frequency of the class of order zero.

Q12. For k attributes the number of ultimate classes is:

A. 2ᵏ   ✓ Correct Answer

B. 1ᵏ

C. 4ᵏ

D. 3ᵏ

Explanation: For k attributes, the number of ultimate (highest order) classes is 2ᵏ.

Q13. For 2 attributes the number of ultimate classes is:

A. 4   ✓ Correct Answer

B. 1

C. 8

D. None

Explanation: For 2 attributes, the number of ultimate classes = 2² = 4.

Q14. In study of attributes, class frequencies are:

A. Enclosed in brackets   ✓ Correct Answer

B. In bold letters

C. In Latin letters

D. None

Explanation: By convention, class frequencies in the study of attributes are written enclosed in brackets, e.g. (AB).

Q15. (αB) denotes the number of objects possessing attribute:

A. B but not A   ✓ Correct Answer

B. A but not B

C. Both A and B

D. All

Explanation: The symbol α represents 'not A', so (αB) denotes objects that possess B but not A.

Q16. In study of attributes no class frequency can be:

A. Positive

B. Negative   ✓ Correct Answer

C. Greater than 0

D. None

Explanation: A valid class frequency can never be negative, since it represents a count of observations.

Q17. In study of attributes, if any class frequency is negative, the data are:

A. Inconsistent   ✓ Correct Answer

B. Consistent

C. Greater than 0

D. None

Explanation: A negative class frequency is impossible for real data, indicating the data set is inconsistent.

Q18. In study of attributes the data are inconsistent if:

A. All ultimate class frequencies are positive

B. Any ultimate class frequency is negative   ✓ Correct Answer

C. The number of attributes are more than two

D. None

Explanation: Data become inconsistent as soon as even one ultimate class frequency turns out negative.

Q19. If no ultimate class frequency is negative, the data would be:

A. Consistent   ✓ Correct Answer

B. Inconsistent

C. Computational error

D. a & c

Explanation: When all ultimate class frequencies are non-negative, the data set is considered consistent.

Q20. There is complete association between attribute A and B if:

A. All A's are B's and all B's are A's

B. All A's are B's   ✓ Correct Answer

C. B's are A's

D. All

Explanation: Complete association between A and B means every A is also a B, i.e. (αβ) = 0.

Q21. There is complete dissociation between attribute A and B if:

A. All A's are B's and all B's are A's

B. All A's are B's

C. B's are A's

D. None of A's is B's and none of α's is β's   ✓ Correct Answer

Explanation: Complete dissociation means A and B never occur together, and their absences never occur together either.

Q22. Disassociation does not imply independence:

A. False

B. Unexplained

C. True   ✓ Correct Answer

D. None

Explanation: This statement is true — attributes can be disassociated (negatively related) without being statistically independent.

Q23. For two attributes A & B, (A), (B), (α), (β) are frequencies of the classes of order:

A. 1   ✓ Correct Answer

B. 2

C. 3

D. None

Explanation: (A), (B), (α), and (β) are each specified by a single attribute, making them classes of order 1.

Q24. For the consistence of a set of class frequencies, no ultimate class frequency should be:

A. Negative   ✓ Correct Answer

B. Positive

C. Zero

D. None

Explanation: Consistency of class frequencies requires that no ultimate class frequency is negative.

Q25. The two attributes A and B are said to be independent if (AB) =

A. (B)(B)/n

B. (A)(A)/n

C. (A)(B)/n   ✓ Correct Answer

D. (A)/(B)

Explanation: Independence between A and B holds when the joint frequency equals (A)(B)/n, mirroring the multiplication rule for independent events.

Q26. (β) =

A. (A)+(α)

B. (B)+(β)

C. (Aβ)+(αβ)   ✓ Correct Answer

D. (AB)+(αβ)

Explanation: (β) is split into those objects that are A but not B, and those that are neither A nor B: (Aβ)+(αβ).

Q27. Yule's coefficient of association lies between:

A. 0 to +1

B. -1 to 1   ✓ Correct Answer

C. -1 to 0

D. None

Explanation: Yule's coefficient of association (Q) ranges from -1 to +1.

Q28. If Yule's coefficient of association Q = 1, then two attributes are:

A. Independent

B. Completely associated   ✓ Correct Answer

C. Completely disassociated

D. None

Explanation: A value of Q = 1 indicates that the two attributes are completely (perfectly) associated.

Q29. If Yule's coefficient of association Q = -1, then two attributes are:

A. Independent

B. Completely associated

C. Completely disassociated   ✓ Correct Answer

D. None

Explanation: A value of Q = -1 indicates that the two attributes are completely disassociated.

Q30. The χ² distribution is:

A. Discrete

B. Continuous   ✓ Correct Answer

C. Discontinuous

D. Undefined

Explanation: The chi-square (χ²) distribution is a continuous probability distribution.

Q31. The value of chi-square (χ²) is always:

A. Negative

B. Positive   ✓ Correct Answer

C. Zero

D. Undefined

Explanation: Since χ² is a sum of squared standardized deviations, it is always non-negative (positive).

Q32. The random variable χ² can assume values:

A. -∞ to 0

B. -∞ to ∞

C. 0 to ∞   ✓ Correct Answer

D. None

Explanation: The chi-square random variable ranges from 0 to infinity, since it can never be negative.

Q33. The parameter(s) of the chi-square distribution is (are):

A. Degrees of freedom   ✓ Correct Answer

B. n-1

C. Mean and variance

D. None

Explanation: The chi-square distribution is characterized entirely by its degrees of freedom.

Q34. The parameter(s) of the chi-square distribution is (are):

A. Two

B. One   ✓ Correct Answer

C. Three

D. Unlimited

Explanation: The chi-square distribution has exactly one parameter: its degrees of freedom.

Q35. The relation Z² = χ² between standard normal and chi-square holds for:

A. Single degrees of freedom   ✓ Correct Answer

B. Two degrees of freedom

C. Three degrees of freedom

D. More than three degrees of freedom

Explanation: The square of a single standard normal variable follows a chi-square distribution with 1 degree of freedom.

Q36. For the better approximation of χ², each expected cell frequency should be:

A. Less than 5

B. At least 5   ✓ Correct Answer

C. Zero

D. None

Explanation: For the chi-square approximation to be valid, each expected cell frequency should be at least 5.

Q37. For one degree of freedom, the relationship between standard normal and chi-square variable is:

A. √χ² = Z

B. Z² = ∛χ²

C. Z = χ²

D. Z² = χ²   ✓ Correct Answer

Explanation: With 1 degree of freedom, the square of the standard normal variable equals the chi-square variable: Z² = χ².

Q38. In χ²-test for independence, the critical region locates:

A. Right tail only   ✓ Correct Answer

B. Left tail only

C. Both tails

D. No critical region

Explanation: For the chi-square test of independence, the critical (rejection) region is located only in the right tail.

Q39. In testing of independence of attributes, the critical region is:

A. χ²cal ≤ χ²table

B. χ²cal < χ²table

C. χ²cal > χ²table   ✓ Correct Answer

D. None

Explanation: The critical (rejection) region is where the calculated chi-square exceeds the table value: χ²cal > χ²table.

Q40. In testing of independence of attributes, null hypothesis is accepted when:

A. χ²cal ≤ χ²table   ✓ Correct Answer

B. χ²cal < χ²table

C. χ²cal > χ²table

D. None

Explanation: The null hypothesis of independence is accepted when the calculated chi-square is less than or equal to the table value.

Q41. In testing of independence of attributes, null hypothesis is rejected when:

A. χ²cal ≤ χ²table

B. χ²cal < χ²table

C. χ²cal > χ²table   ✓ Correct Answer

D. None

Explanation: The null hypothesis is rejected when the calculated chi-square exceeds the table value.

Q42. If χ²cal < χ²table then attributes are:

A. Not associated   ✓ Correct Answer

B. Dependent

C. Associated

D. None

Explanation: When the calculated value is less than the table value, we fail to reject independence, so the attributes are not associated.

Q43. Greater the value of χ²:

A. More chance of rejecting H₀   ✓ Correct Answer

B. More chance of rejecting H₁

C. More chance of accepting H₀

D. No decision

Explanation: A larger chi-square value pushes further into the critical region, increasing the chance of rejecting the null hypothesis (H₀).

Q44. Coefficient of contingency applied when:

A. H₀ is rejected   ✓ Correct Answer

B. H₁ is rejected

C. H₀ is not rejected

D. None

Explanation: The coefficient of contingency is used to measure the strength of association once H₀ (independence) has been rejected.

Q45. For test of independence of r x c contingency table, degrees of freedom are:

A. (r-1)(c-1)   ✓ Correct Answer

B. (r+1)(c+1)

C. (r+1)(c-1)

D. (1-r)(1-c)

Explanation: For an r × c contingency table, the degrees of freedom for the independence test are (r-1)(c-1).

Q46. A contingency table is made up of the observed frequencies relative to the:

A. Two attributes   ✓ Correct Answer

B. Three attributes

C. Four attributes

D. None

Explanation: A contingency table classifies observed frequencies according to two attributes simultaneously.

Q47. To test the independence of attributes we use:

A. Z-test

B. F-test

C. t-test

D. χ²-test   ✓ Correct Answer

Explanation: The chi-square (χ²) test is the standard test used to check independence between attributes.

Q48. Rank correlation is used in case of:

A. Ratio scale

B. Interval scale

C. Nominal scale

D. Ordinal scale   ✓ Correct Answer

Explanation: Rank correlation is designed for ordinal (ranked) data, where only the order of values matters.

Q49. Rank correlation is used when relationship between variables is:

A. Linear

B. Perfect linear

C. Non-linear   ✓ Correct Answer

D. None

Explanation: Rank correlation is especially useful when the relationship between variables is non-linear, since it depends only on ranks.

Q50. The value of rank correlation coefficient lies between:

A. 0 to 1

B. -1 to 0

C. -1 to +1   ✓ Correct Answer

D. 0 to ∞

Explanation: Like other correlation coefficients, the rank correlation coefficient ranges from -1 to +1.

Q51. The value of rank correlation coefficient is -2:

A. Correct

B. There may be a computational error   ✓ Correct Answer

C. Perfect negative correlation

D. No correlation

Explanation: Since rank correlation must lie between -1 and +1, a value of -2 is impossible and indicates a computational error.


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