Statistical Inference: Types, Procedure & Examples

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Arpita Srivastava

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Statistical inference is defined as the process of analysing data and drawing conclusions based on random variation. Hypothesis testing and confidence intervals are two applications of statistical inference. 

  • Statistical inference is a technique that uses random sampling to make decisions about the parameters of a population. 
  • The method is based on the concept of probability distribution.
  • It allows us to evaluate the relationship between the dependent and independent variables. 
  • Statistical inference aims to estimate the uncertainty or variation from sample to sample. 
  • It enables us to provide a range of value for something's true worth in the population.
  • The process involves the collection of quantitative data.
  • Descriptive Statistics and Inferential Statistics are two types of Statistical inference.
  • Polling performed during the election is a real-life example of the inference.

The components used in the statistical inference are as follows:

  • Size of the sample
  • Sample Size
  • Variability in the sample

Key Terms: Statistical Inference, Probability Distribution, Independent Variables, Dependent Variable, Descriptive Statistics, Inferential Statistics, Bivariate Regression, Multivariate Regression, Anova or T-test, Chi-Square Statistic, Contingency Table


Types of Statistical Inference

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Different types of statistical inference which are used to draw conclusions are as follows:

Pearson Correlation Coefficient 

Pearson Correlation Coefficient is a type of coefficient that specifies the ratio between the covariance of two variables and the product of their standard deviations. 

  • The value ranges between -1 to 1.
  • It can be mathematically represented as:

p x,y = cov (x, y) / σx σy

Bivariate Regression

Bivariate Regression Analysis is a form of analysis that specifies the relationship between two variables. It is used for testing the hypothesis of variables. The analysis determines the strength of the relationship between variables.

 y = β0 + β1 x + ε

Multivariate Regression

Multivariate Regression is a type of regression that specifies the degree to which more that one dependent variables are related to independent variable. It is the simplest Machine Learning Algorithm.

Y = β0 + β1X1+ βkXk + residual

Anova

Anova also known as analysis of variance is a statistical model that is used to determine the relationship between independent variables and the dependent variable. 

T-test

T-test is an important method is used in the field of statistical inference that determine the difference between the means of two groups. It determine the relationship between two grouped data.

  • It can be represented as:

t = m – μ / (s/ √n)

However, the most common and widely used types of statistical inference are

  • Interval of Confidence
  • Validation of hypotheses

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Statistical Inference Procedure

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The Statistical Inference Procedure includes the steps listed below which are as follows:

  • Firstly, start with a theory.
  • In the next step, create a research hypothesis.
  • Put the variables into action.
  • Then, recognize the population to which the findings should be applied.
  • Create a null hypothesis for this population.
  • Begin the study by gathering a sample of children from the general population.

To reject the null hypothesis, use the statistical test to see if the collected sample properties differ from what is expected under the null hypothesis.

Statistical Inference

Statistical Inference 


Statistical Interference Solution

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Statistical inference solutions make effective use of statistical data in relation to a group of individuals or trials. It deals with every character, including data collection, investigation, and analysis, as well as data collection organization. 

  • People can gain knowledge after starting work in a variety of fields by using statistical inference solutions. 

The following are some statistical inference solution facts:

  • It is a common method for predicting whether the observed samples are independent of a specific population type.
  • The method includes poisson or normal distribution methods.

The statistical inference solution aids in evaluating the expected model's parameter(s), such as normal mean or binomial proportion.


Importance of Statistical Inference

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The importance of statistical inference is that it helps examine the data properly. To develop an effective solution, accurate data analysis is required to interpret the research findings. 

  • Inferential statistics is used to forecast the future based on a variety of observations from various fields. 
  • It allows us to draw conclusions about the data. 
  • The method also assists us in providing a likely range of values for the true value of something in the population.

Statistical inference is used in a variety of fields, including:

  • Business Analysis
  • Artificial Intelligence
  • Financial Analysis
  • Fraud Detection
  • Machine Learning
  • Pharmaceutical Sector
  • Share market.

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Things to Remember 

  • Statistical inference is used to test hypotheses and calculate confidence intervals.
  • It is also referred to as inferential statistics. 
  • The method consists of analyzing and drawing conclusions from data that is subject to random variation.
  • It employs a variety of statistical analysis techniques to reach a conclusion about the population. 
  • In statistics, descriptive statistics are used to describe data.
  • On the other hand, inferential statistics are used to make predictions based on the data. 
  • Inferential statistics uses data from a sample to generalize to the entire population. 
  • The students can take help from Class 12 Mathematics Notes.

Sample Questions 

Ques: A card is drawn from the shuffled pack of 52 cards. The trial is repeated a total of 400 times, and the different suits of cards are listed below:

Suit

Spade

Clubs

Hearts

Diamond

No of times cards drawn 

90

100

120

90

What is the likelihood of receiving the following suits if the card is drawn at random? (5 marks)

(A) Diamond Card

(B) Black Card

(C) Except for spade

Ans: Through statistical inference solution. 

Total number of events = 400

i.e., 100 + 90+120+90 = 400

(A) The probability of winning a diamond card is:

Total number of trials in which diamond card is drawn= 90

Hence, P(diamond card )= 90/4000

= 0.22

(B) The probability of winning black card is:

Number of trials in which black card appeared = 100 + 90 = 190

Hence, P(black card) = 190./400 = 0.48

(C) Except spade

Number of trials other than spade appeared = 90 + 100 + 120 = 310

Hence, P(except spade) = 310/400 = 0.78

Ques: A bad with two yellow balls, three red balls, and five black balls. From the bag, only one ball is drawn at random. What is the likelihood of drawing the black ball? (3 marks)

Ans: Through statistical inference solution.

  • Total number of balls in a bag = 10
  • i.e 2 + 3+ 5 = 10
  • Number of black balls= 5
  • Probability of getting a black ball = Number of black balls/ Total number of balls
  • 5/10 
  • 1/2

Hence, the probability of getting black balls is 1/2.

Ques: A card is drawn at random from a deck of 52. What is the likelihood that the card drawn is a face card (only the Jack, King, and Queen)? (3 marks)

Ans: Total number of cards= 52

  • Number of a face card in a pack of 52 cards= 12
  • Probability of receiving a face card = 12/52 = 3/13
  • Hence, the probability of receiving face card is 3/13

Ques: What exactly is statistics? Describe its various types. (5 marks)

Ans: Statistics is the in-depth study of data collection, organisation, interpretation, and presentation. It is, in other words, a type of mathematical analysis that collects and summarises data. It is used in a variety of fields including business, manufacturing, psychology, government, manufacturing, humanities, and so on.

  • Statistics data is gathered through the use of a sample procedure or other methods.
  • Descriptive statistics and inferential statistics are the two types of statistical procedures used to analyse data.
  • Inferential statistics are used to assess data from a sample using the mean or standard deviation.
  • Descriptive statistics are used to assess data from a sample using the mean or standard deviation.

The statistic is divided into two categories. There are two kinds of statics:

  • Descriptive Statistics
  • Inferential Statistics

Ques: What Is the Purpose of Statistical Inference Training? (3 marks)

Ans: Inferential statistics use data from a sample to draw conclusions about the larger population from which the sample was drawn. The goal of statistical inference is to draw conclusions from a sample and apply them to a large population.

  • It employs probability theory to investigate the probabilities of sample characteristics.
  • The most commonly used methods are hypothesis tests, analysis of variance, and so on.

Ques: Find the probability of getting an odd number when a die is tossed? (2 marks)

Ans: When a die is tossed there are 6 possible outcomes, S = { 1, 2, 3, 4, 5, 6 }

According to the question, favorable events of getting an even number is { 1,3,5 }

Therefore, no. of favorable event = 3

And the total no. of outcomes = 6

Therefore, the probability of getting an odd number when a die is tossed is 3 / 6 = 1 / 2

Ques: A bad with three yellow balls, three red balls, and six black balls. From the bag, only one ball is drawn at random. What is the likelihood of drawing the yellow ball? (3 marks)

Ans: Through statistical inference solution.

  • Total number of balls in a bag = 12
  • i.e 3 + 3+ 6 = 12
  • Number of yellow balls= 3
  • Probability of getting a black ball = Number of yellow balls/ Total number of balls
  • 3/12
  • 1/4

Hence, the probability of getting yellow balls is 1/4.

Ques: What is the probability of getting a sum of 8 when two dice are thrown? (3 marks)

Ans: There are 36 possibilities when we throw two dice.

The desired outcome is 8. To get 8, we can have three favorable outcomes.

{(4,4),(6,2),(5,3),(3,5), (2,6)}

Probability of an event = number of favorable outcomes/ sample space

Probability of getting number 8 = 5/36 

Ques: The correlation coefficient of a set of data is found to be 0.9. The standard deviation of data set x (σx) = 1 , and standard deviation of data set y (σy) = 1.4. Find out the covariance of the data? (3 marks)

Ans: The relationship between correlation and covariance is given by –

Correlation = p x,y = cov (x, y) / σx σy

Values given in the question are,

  • Correlation = 0.9
  • σx = 1
  • σy = 1.4
  • Therefore, cov(x,y) = 0.9 x 1 x 1.4
  • 1.26

Ques: What does a correlation of 0.66 means? (2 marks)

Ans: As we know that a correlation of 1 means a perfect positive correlation, thus, a correlation of 0.66 means 66% of the variance in one variable is accounted for by the second variable.

Ques: Find the standard deviation of 4, 9, 11, 15, 17, 5, 8, 12, 10? (4 Marks)

Ans: First find out the mean: 10.11

Now, subtract the mean individually from each of the data set points provided and then square the obtained result, which is equivalent to the (x - μ)² step. 

x would refer to the values given in the question.

X 4 9 11 15 17 5 8 12 10
(x - μ)² 37.33 1.23 0.79 23.91 47.47 26.11 4.45 3.57 0.0121

Now, add up the obtained results (which is the 'sigma' in the formula): 144.87

Now, divide by n. as discussed earlier n is the number of values in the data, so in this example, N is 9. which gives us: 16.09

And lastly, square root it: 4.01


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    • 2.
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        • 3.

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                • 5.
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                      CBSE CLASS XII Previous Year Papers

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