
You get to understand all about sampling in statistical studies. You will get to understand the answers to the following questions
What is the role of sampling in statistical studies?
What is a representative sample?
What is bias in Sampling?
What are the different kinds of biases that occur during sampling?
What is selection bias? What is measurement and non-responsive bias? What is response bias?
What is simple random sampling?
What is sampling with replacement and sampling w/o replacement?
Why simple random sampling results in a representative sampling more often than not?
What are the other alternative sampling methods available and when are they deployed?
At the end of this lecture you get to understand on the following, underlying concepts & methods and illustration of application of the methods via real life examples
How does a sample mean relate to the population mean?
How does one go about generalizing the sample mean to the population mean?
Does the sample mean vary between samples of a given size?
Is there a definite probability distribution for the sample mean when repeated over a large number of times?
What is the mean? What is the standard deviation? of the sample mean distribution
How is the mean of the sample mean distribution related to the population mean?
How is the standard deviation of the sample mean distribution related to the population standard deviation?
How does sample size influence the (variance) the standard deviation of the sample mean distribution?
What is central limiting theorem?
How to arrive at the z or t statistic from the sample mean?
How to make judgements about the population mean using the z statistic?
At the end of this lecture you get to understand on the following, underlying concepts & methods and illustration of application of the methods via real life examples
What is population proportion of success?
What is sample proportion of success?
What does the probability distribution of sample proportion p look like?
How does the mean of sample proportion distribution relate to population proportion of success π?
How does the Standard deviation of sample proportion distribution σp relate to population proportion of success π?
What is the criteria for the sample proportion distribution to be approximately normal?
How to arrive at the z statistic for a given sample proportion?
How do we go about making judgements about the population proportion of success using the z statistic?
This topic is split into two lectures. This lectures mainly lays emphasis on the following concepts and methods and deals with them in detail
What is a point estimate?
How to estimate an unknown true population characteristic using a single point estimate?
What is a biased statistic?
How does variability in sample statistic distribution play a role in estimating the true value of the population characteristic?
What is a confidence level?
What is a confidence interval?
How to estimate a confidence interval for a given confidence level?
This is the second lecture on this topic. This part deals with
How to apply the general expression for confidence interval to sample proportion distributions?
How to apply the general expression for confidence interval to sample mean distributions?
What is bound on error and how to arrive at a sampling size based on bound on error?
What is t-distribution and when to apply the same?
Summary of the the key points to remember in handling the confidence intervals
And finally illustrating the concepts and methods discussed in these two parts with two examples one each from sample mean distribution and sample proportion distribution
Statistical studies are often about understanding, estimating various population characteristics.
Since it is often not feasible to undertake the study on the entire population the statistical study is often carried out on a representative sample drawn out of the population
Therefore the said sample has to meet certain expectations in order to be a fairly good representative of the population.
This course starts with the topic that explain the factors to be understood and implemented as part of the sampling process
From the sample a sample statistic representing a population characteristic of interest is derived. Population characteristic of interest is often one among the following two {Population proportion of success, Population mean}
A sample statistic is a single sample point estimate of the population characteristic. Therefore the sample statistic exhibits a probability distribution as sampling and sample statistic are derived repeatedly over large number of cycles. This course explains the characteristics of such a sample statistic distribution for both kinds of sample statistics namely { Sample proportion of success, Sample mean}. Explains the mean and standard deviations for these distributions and how they are related to population characteristics and sampling sizes.
The course further explains how to use the sample statistic (single sample Point estimate) to get an idea of the population characteristic using an additional estimate called as the confidence interval. Point estimate and confidence interval together identify the interval that captures the true unknown population characteristic.
The course also explains how to apply the Z standard normal statistic , t-statistic and their respective Z/T statistic tables in the above process to arrive at the estimates for the population characteristics.
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