# Statistical Methods (ISS (Statistical Services) Statistics Paper I (Old Subjective Pattern)): Questions 51 - 54 of 72

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## Question number: 51

» Statistical Methods » Non-Parametric Test » Wilcoxon

Appeared in Year: 2012

### Describe in Detail

Ten short-distance runners were put to a rigorous training for two months. Times taken by them to clear 100 metres before and after the training were as follows:

Sl. no. of runner | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |

Time (in sec) before training | 10.6 | 10.9 | 10.1 | 10.5 | 11.0 | 11.2 | 10.7 | 10.2 | 10.9 | 10.6 |

Time (in sec) after training | 10.1 | 10.7 | 9.9 | 10.0 | 11.1 | 10.9 | 10.6 | 10.3 | 10.5 | 10.8 |

Use Wilcoxon’s paired sample signed rank test to examine at 1 % level if the training was at all effective. (The critical value of Wilcoxon’s statistic at 1 % level of significance for n = 10 is 5)

### Explanation

In Wilcoxon’s paired sample signed rank test, the null hypothesis that we are sampling two continuous symmetric populations with for the paired-sample case, we rank the differences of the paired observations without regard to sign and proceed as in the single-sample case

Let and represent the median

## Question number: 52

» Statistical Methods » Non-Parametric Test » Run

Appeared in Year: 2013

### Describe in Detail

Describe the run test for randomness. For the sequence of outcomes of 14 tosses of a coin,

HTTHHHTHTTHHTH, .

test whether the outcomes are in random order. (Given the lower and upper critical values R _{L} = 3,

R _{u } = 12 at 0.05 significance level. )

### Explanation

Suppose a sample size n contains n _{1} symbols of one type and n _{2} symbols of the other type. The null hypothesis is the symbols occur in random order, the alternative is the symbols occur in a set pattern. The lower and upper critical value is obtained from tables.

## Question number: 53

» Statistical Methods » Correlation Coefficient » Multiple Correlation

Appeared in Year: 2015

### Describe in Detail

With 3 variables X _{1}, X _{2} and X _{3}, it is given that r _{13} =0.71, R _{1.23} =0.78. Find r _{12.3}.

### Explanation

We know that

The relationship between the partial and multiple correlations is

## Question number: 54

» Statistical Methods » Correlation Coefficient » Intraclass Correlation

Appeared in Year: 2012

### Describe in Detail

For a set of 10 pairs of observations (x _{i}, y _{j}), i = 1 (1) 10, the following calculations are available

Examine at 5 % level of significance if the two variables arc uncorrelated in the population.

### Explanation

First, we calculate the sample correlation coefficient r

for i = 1 to 10

Putting the value in the formula for n = 10

The test hypothesis is

The test statistic is the t-test

The tabulated value is t _{0.05, 8}