how to conduct a simple random sample
the simple random sampling process entails six steps each performed in sequential order the origin of statistical analysis is to determine the population base this is the group for which you wish to learn more confirm a hypothesis or determine a statistical outcome this step is to simply identify what that population base is and ensure that the group will adequately cover the outcome you are trying to ascertain example you want to learn how the stocks of the largest companies in the united states have performed over the past 20 years your population would be the largest companies in the united states as determined by the s p 500 before picking the units within a population we need to determine how many to select this sample size may be constrained by the amount of time capital rationing or other resources available to analyze the sample however be mindful to pick a sample size large enough to be genuinely representative of the population in the example above there are constraints in analyzing the performance for every stock in the s p 500 so we only want to analyze a subset of this population example your sample size will be 20 companies from the s p 500 in our example the items within the population are easy to determine as they ve already been identified for us i e the companies listed within the s p 500 however imagine analyzing the students currently enrolled at a university or food products being sold at a grocery store this step entails crafting the entire list of all items within your population example using exchange information you copy the companies comprising the s p 500 into an excel spreadsheet the simple random sample process calls for every unit within the population to receive an unrelated numerical value this is often assigned based on how the data may be filtered for example you could assign the numbers one to 500 to the companies based on market cap alphabetical order or company formation date how the values are assigned isn t relevant all that matters is that each value is sequential and has an equal chance of being selected example you assign the numbers one through 500 to the companies in the s p 500 based on alphabetical order of the current ceo with the first company receiving the value one and the last company receiving the value 500 in step 2 we chose 20 as the number of items we wanted to analyze within our population we now randomly select 20 number values out of the 500 there are multiple ways to do this as discussed later in this article example using the random number table you select the numbers 2 7 17 67 68 75 77 87 92 101 145 201 222 232 311 333 376 401 478 and 489 each of the random variables selected in the prior step corresponds to an item within our population the group sample is selected by identifying which random values were chosen and which population items those values match example your sample consists of the companies that correspond to the values chosen in step 5 random sampling techniquesthere is no single method for determining the random values to be selected in step 5 the analyst can t choose completely random numbers on their own as there may be factors influencing their decision for example the analyst s wedding anniversary may be the 24th so they may consciously or subconsciously pick the random value 24 instead the analyst may choose one of the following methods 