Perform Chi square using Microsoft excel for outbreak investigation
What is Chi-Square Analysis? Chi-Square is a non-parametric analysis that enables the researcher to test the hypothesis about the data distribution for nominal or categorical data. How you can be performed this analysis of data for chi-square analysis using the excel. As you know some of the data analyst or researcher probably did not have the commercial software to compute the analysis of the chi-square.
This article, we are going to discuss the step by step analysis of chi-square in the ms excel. The importance of this analysis was to investigate the associated/ influential factors of the exposure to the status of health for the respondents. The chi-square analysis that is used will be the chi-square testing for the independence. To learn more and straightforward explanation, please refer to the videos as provided.
The data used for this exercise can be download here. The hypothesis steps for this analysis can be described as follows:
State your null and alternative hypothesis
State/ set your alpha values
Run/ calculate (in this case, we are going to use the excel)
Decision making (reject or fail to reject the null hypothesis)
Making your null and alternative hypothesis:
Null: There is no significant association between the status of exposure with the status of health (between control and case)
Alternative: There is a significant association between the status of exposure with the status of health (between control and case)
Figure 1. Null and Alternative hypothesis
Setting up your alpha. Usually, the researcher is going to set the alpha will be 0.05
Run or calculate the chi-square values
Figure 2. Analysis steps of the chi-square
Making decision. In this example, we are going to reject our null hypothesis due to the fact that the p-value less than our alpha sets in step 2. Besides, we also will look into the value of the chi-square 4.13865 which is more than the levels of the alpha sets under the area under the curve (3.8415). Therefore we finally reject the null.
Making conclusion. Therefore, we are going to state that there is a significant association between the status of exposure with the status of health (between control and case). In this case, the orange drink was the probably factors that will influence the disease distribution of the outbreak.
Chi-Square Application in Disease Outbreak Investigation
The application of this analysis can be further checked or be calculated also using the Epi Info software. By doing this analysis, epidemiologist, public health officer or environmental health professionals, can further take actions towards the control of the spreading of disease or further investigate the process of making the food/ preparation of the drinks. To learn more about the data analysis using the chi-square statistics for outbreak investigation, please refer to this link.
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