Data collection is one of the most important steps when carrying out any study, since it is these figures that provide the true and necessary information about the phenomenon to be consulted. Among the tools that can be used to collect and organize data, there are frequency tables, which are statistical tools , essential in any type of analysis that studies a population, and therefore, a sample, since These tables are used to order the data in the correct way, classify the information and, therefore, obtain really correct results and not only correct ones.
What is the usefulness of frequency tables?
This is an extremely important tool, since it captures the values that represent the variable, together with the times that these are repeated within the sample, all this, with the aim of displaying the information in a simple and effective way. In addition to this, other benefits are obtained by using this class of tables, among which the following can be mentioned:
They report on the behavior of a population
By filling in a frequency table with the information collected, it is possible to appreciate the way in which a population acts or reacts to certain stimuli or situations through the chosen sample.
For example, if a laboratory is testing the effectiveness of a drug, it should record in a frequency table the number of people in which it was used, the number of times it was applied and the amount in which it obtained good results. or bad results; all this, with the aim of determining the effectiveness of the drug.
The frequency tables allow you to organize all this data in one place; and best of all, it allows us to see the effectiveness of the drug, on the population sample with which it has been experimented.
They allow the elaboration of graphics
Once the researcher has obtained all the necessary data, he will be able to make graphs based on this information. This will help visually to identify the variation between one value and another, for a given time. Histograms are generally performed for their simplicity and ease of reading.
They facilitate the analysis and interpretation of data
After doing everything necessary to collect and organize the data, the researcher must conclude with the results, which will be the product of analyzing and interpreting the tables prepared. This stage is essential to complete the research, since it will be possible to make decisions about the measures applicable to the population (in case the study has been done with the purpose of modifying the observed behavior, since the study, also can be applied, to try to improve a product and make it more accepted by the population)
To complete this process, use can be made of central tendency measures, which have the ability to provide all the necessary information about how the data is distributed.
The data collected in the investigation can be tabulated in different types of tables, this will depend on several factors, such as the intrinsic characteristics of the variables (discrete or continuous), the amount of data and the size of the sample. There are two classifications to group these types:
According to the nature of the data
Depending on the type of data, the following should be taken into account:
- From non-grouped data : a simple frequency table or from non-grouped data, shows the database as it was collected in the research. This type of table occurs in analyzes involving discrete variables (values can only take whole numbers, for example: number of children per family) and for small sample sizes.
- Of grouped data : they are those that collect and order large amounts of information. To use this type of table, it is necessary that the variables studied are continuous (capable of adopting decimal values without the final result losing meaning, such as the distance in km from one place to another)
According to the number of variables
In these cases, two types of tables can be applied:
- Univariate : they include the use of a single variable to carry out the study; For example, to measure the average income of families in an area, it will only be necessary to take into account the monthly salary of all families in the sample.
- Bivariate : it shows the relationship of two variables for a single investigation, giving information about the influence of one variable on the other and vice versa. A clear example would be trying to know how income is related to education in the population, for this, variables such as monthly income and the level of education of the head of the family must be included in the same table.
How are the frequency tables formed?
It can be said that the elements of the tables are all those columns that must be filled in, with the data collected through the surveys previously carried out. Having clarified this, the following should be understood:
This element denoted by the letters “ni”, quantifies the number of times that a piece of data is repeated in the analysis. The sum of this column results in the sample size (n).
Cumulative absolute frequency
This column shows the sum of all the lower absolute frequencies, therefore, the final value must always be equal to the total sum of the absolute frequencies, which is equal to n. This column is called “Ni”.
It is denoted by the letters “fi”, and shows the proportion of times each piece of data is repeated, expressed as so much per one. This value is the result of dividing each absolute frequency by the sample size, that is, ni / n.
Cumulative relative frequency
Displays the cumulative proportions as you progress through the table. The final value of this column must be equal to 1 or, failing that, some very close number (0.99 for example). It is represented by the letters “Fi”.
A class mark is the midpoint of an interval, it is denoted by the letters “Xi”. It serves to simplify the study in numerical terms, since each box consists of a single value, that is; this column is used to calculate all statistical parameters.
How to make a frequency table?
The first thing is to do the data collection; This must be done through a survey instrument, which allows gathering all the information necessary for the study. The survey should only be applied to the population that meets the characteristics of the study, since only then will there be complete and perfect information on the phenomenon to be observed.
Once the information is gathered, the selection of the representative sample must be made, this is a completely random selection, which is why it is concluded that the total population will have the same behavior as the sample. Finally, all the information must be carefully emptied into the corresponding columns.
Conclusion: Are frequency tables important?
The frequency tables are highly recommended, since they can be handled without having deep knowledge in the area; even so, it is very useful in any work field, because in this way the large databases are ordered worldwide. As a result of this, they can be considered very useful; since it fulfills its function and they are easy to use.
Dr. Samantha Robson ( CRN: 0510146-5) is a nutritionist and website content reviewer related to her area of expertise. With a postgraduate degree in Nutrition from The University of Arizona, she is a specialist in Sports Nutrition from Oxford University and is also a member of the International Society of Sports Nutrition.