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## Freshers / Beginner level questions & answers

### Ques 1. What is the difference between population and sample?

Population refers to the entire group under study, while a sample is a subset of the population.

Example:

Population: All students in a university. Sample: 100 students randomly selected from the university.

### Ques 2. What is p-value in statistics?

The p-value is the probability of obtaining results as extreme as or more extreme than the observed results under the assumption that the null hypothesis is true.

Example:

If p-value is 0.05, there is a 5% chance of observing the results if the null hypothesis is true.

### Ques 3. Define standard deviation.

Standard deviation is a measure of the amount of variation or dispersion in a set of values. It represents the average distance of each data point from the mean.

Example:

For a set of test scores: 70, 72, 75, 78, 80. Standard deviation is approximately 3.16.

### Ques 4. What is the difference between a population parameter and a sample statistic?

A population parameter is a numerical value that describes a characteristic of an entire population. A sample statistic is a numerical value that describes a characteristic of a sample drawn from that population.

Example:

Population parameter: Average income of all households. Sample statistic: Average income of a sample of 100 households.

### Ques 5. Define the term 'confidence level' in the context of confidence intervals.

The confidence level is the probability that the calculated confidence interval contains the true population parameter. Common confidence levels are 90%, 95%, and 99%.

Example:

A 99% confidence interval for the average weight of a certain species of bird is 20 to 25 grams.

### Ques 6. What is a histogram, and how is it used in statistics?

A histogram is a graphical representation of the distribution of a dataset. It displays the frequencies of different ranges or bins of the data, providing insights into its shape and central tendency.

Example:

Creating a histogram to visualize the distribution of exam scores in a class.

### Ques 7. What is the purpose of a box plot (box-and-whisker plot)?

A box plot is used to display the distribution and spread of a dataset. It shows the median, quartiles, and potential outliers in a compact visual format.

Example:

Comparing the distribution of salaries in different departments using box plots.