14th Session- Understanding Sampling

                                                                                                   

The Session began with a revision of concepts studied in the last class. i.e the distinction between chi-square and T-test methods  and their applicability under different situations. For eg : We have two groups of 6 people each  with similar age groups. One of these groups is administered with a drug. The effect of this medicine shall constitute the output and it shall be a continuous variable.

Sampling

Census is an example where the population is calculated using a sample . 

Sample should be made aas representative of the population. If this is achieved then a small sample will do and the cost benefit shall also be achieved. 

Target population is the people we want to target and is smaller than the cenus

Sampling frame is a list of all the respondents within a sample.

Sample  is the  smallest representation of the people.

Methods of Sampling

1)      Probability sampling

a)      Simple Random

b)      Systematic Random : From the sampling frame we decide a certain number of observations we require at regular intervals. Which number to start with may be decide in a number of ways.

c)       Cluster Sampling : The sample is more representative of the population because it has different elements of population.

d)      Stratified Sampling : In stratified sampling we have uniformity i.e. we find all our samples at one place.

Benford's Law : It refers to the frequency refers to frequency distribution of the digits in many real life sources of data. In this distribution,the number 1 occurs as the leading digit about 30% of the time,while larger numbers occurs in that position less frequently,9 as the first digit less than 5% of the time.

Non-Probability methods

1)      Convenience sampling: Convienence sampling is a non-probability sampling where subjects are selected because of thier conveinent accessibility and proximity to the researcher.

2)      Judgement sampling : When take the opinion of an expert as to where we can get a good sample,it is called judgement sampling.

3)      Quota Sampling : The sample is in the same proportion of elements as the population

4)      Snowball or reference sampling : This is a non probabilty technique where existing study subjects recruit future subjects among thier acquaintances.

Written By,

Nishidh Lad

Group Members

Nishidh Lad

PPriyadarshi Tandon

Priyathaam Kireeti

Kalyani Pakala

p.Karteeki