That is a nice question, I need to emphasize that SPSS stores the data that will be analyzed in the numeric format. So once you change the “variable view –> type” to numeric, SPSS can analyze it. When you change the “type” to numeric (variable view –> type –> numeric), you have to adjust also manually the “Measure” to assign it to either scale (if the variable is a number e.g. age, gender), “nominal” (if the variable is groups and each group is coded as 1, 2, etc.) or “ordinal” (if the variable groups should be graded e.g. grade 1, grade 2 or level 1, level 2, etc.).
If you change the “Type” to “string”, you instruct SPSS to ignore this variable in the analysis.

Dr. Fatma
Please do not be confused. It is so easy. Odds ratio of 1 means no risk. Odds ratio of more than 1 means there is risk. Odds ratio of less than 1 means that the factor or the variable is protective against risk and and not of risk. This is the meaning of the odds ratio.

There is another issue which is : if there is risk or protection against risk, is it significant or not significant? In this situation you have to look at the limits of the confidence interval. If the odds ratio is more than 1 and the lower limit of the confidence interval is 1 or more than 1, this means that the risk is significant. But if the lower limit of the confidence interval is less than 1, this means that the risk is not significant.

On the other hand, if the odds ration is less than 1 and the upper limit of the confidence interval 1 or less than one, then the factor is significantly protective. But if the upper limit of the confidence interval is more than 1, this means that the factor is not significantly protective.

Dr. Fatma
Is it clear now? Please let me know your impression. Thank you very much for your question.

Hi doctor
I knew that
Todd’s ratio = probability of presence of a disease divide the probability of absence of that disease
Or
= probability of presence of disease divide 1 – probability of presence of the disease
Is this formula right?

Dr. Ola
Thank you very much for your question. The expression is called Odds ratio (OR) not Todds ratio. It is a way for expression of presence of risk and used in retrospective studies or case-control studies. Odds ratio of 1 means no risk. Odds ratio of 10 means that the probability of presence of a risk factor causing the disease is 10 times if the disease is present compared to the probability of exposure to the risk factor causing the disease if the disease is absent.

You do not need to calculate it by yourself, it will be calculated by the computer automatically upon request. All what you need to know is the meaning of the expression and its value in any study. I explained the formula in my lecture as a way of clarification, but if it is causing confusion you can ignore it.

Dr. Ola
Please let me know that if my answer is satisfactory and clear for you or not.

Dr. Moustafa
Your understanding is absolutely right. The 3 expressions carry the same meaning which is expression of risk but each of them is used according to the study design. Odds ratio (OR) is used in retrospective or case-control study, relative risk (RR) is used in prospective or cohort study, while hazard ratio (HR) is used in studies including time such as survival rate, tumor recurrence rate or cancer progression rate….etc.

Dr. Moustafa
Cohort study is a type of study design. It means prospective study. According to Oxford dictionary the word cohort means a companion or a colleague, but if the word cohort is used to describe a study, it means a prospective study, it will not be just an English word, it means a special study design.
Please be informed that there will be several lectures discussing the types of designs of medical studies in Module #2 of this course.

Dr. Moustafa
Please let me know if my answers for the 2 questions were clear or not.

Dr. Moustafa
I want to know the impression regarding the third lecture. Was it clear, because I have not received any comments or questions from the participants.

hello dr

i wanna ask if we import the excel file and edit the types .if the rest of measure and value will be changed also?

Dear Dr. Fatrma,

That is a nice question, I need to emphasize that SPSS stores the data that will be analyzed in the numeric format. So once you change the “variable view –> type” to numeric, SPSS can analyze it. When you change the “type” to numeric (variable view –> type –> numeric), you have to adjust also manually the “Measure” to assign it to either scale (if the variable is a number e.g. age, gender), “nominal” (if the variable is groups and each group is coded as 1, 2, etc.) or “ordinal” (if the variable groups should be graded e.g. grade 1, grade 2 or level 1, level 2, etc.).

If you change the “Type” to “string”, you instruct SPSS to ignore this variable in the analysis.

hello dr

i really confused about the odds ratio if it less than 1 ..its statistically significant or not

Dr. Fatma

Please do not be confused. It is so easy. Odds ratio of 1 means no risk. Odds ratio of more than 1 means there is risk. Odds ratio of less than 1 means that the factor or the variable is protective against risk and and not of risk. This is the meaning of the odds ratio.

There is another issue which is : if there is risk or protection against risk, is it significant or not significant? In this situation you have to look at the limits of the confidence interval. If the odds ratio is more than 1 and the lower limit of the confidence interval is 1 or more than 1, this means that the risk is significant. But if the lower limit of the confidence interval is less than 1, this means that the risk is not significant.

On the other hand, if the odds ration is less than 1 and the upper limit of the confidence interval 1 or less than one, then the factor is significantly protective. But if the upper limit of the confidence interval is more than 1, this means that the factor is not significantly protective.

Dr. Fatma

Is it clear now? Please let me know your impression. Thank you very much for your question.

Hi doctor

I knew that

Todd’s ratio = probability of presence of a disease divide the probability of absence of that disease

Or

= probability of presence of disease divide 1 – probability of presence of the disease

Is this formula right?

Dr. Ola

Thank you very much for your question. The expression is called Odds ratio (OR) not Todds ratio. It is a way for expression of presence of risk and used in retrospective studies or case-control studies. Odds ratio of 1 means no risk. Odds ratio of 10 means that the probability of presence of a risk factor causing the disease is 10 times if the disease is present compared to the probability of exposure to the risk factor causing the disease if the disease is absent.

You do not need to calculate it by yourself, it will be calculated by the computer automatically upon request. All what you need to know is the meaning of the expression and its value in any study. I explained the formula in my lecture as a way of clarification, but if it is causing confusion you can ignore it.

Dr. Ola

Please let me know that if my answer is satisfactory and clear for you or not.

Hi colleagues, I’ll be happy to answer any queries you have regarding the SPSS program.

Thanks Prof Shokier.

Do the relative risk, odds ratio and hazard ratio have the same principle but differ for the study type showing the strength relationship?

Do I’m understanding correctly?

Dr. Moustafa

Your understanding is absolutely right. The 3 expressions carry the same meaning which is expression of risk but each of them is used according to the study design. Odds ratio (OR) is used in retrospective or case-control study, relative risk (RR) is used in prospective or cohort study, while hazard ratio (HR) is used in studies including time such as survival rate, tumor recurrence rate or cancer progression rate….etc.

Thank you Dr Shokier

Dr. Moustafa

You are most welcome.

Is the name cohort is an abbreviation to something or a name of someone?

Dr. Moustafa

Cohort study is a type of study design. It means prospective study. According to Oxford dictionary the word cohort means a companion or a colleague, but if the word cohort is used to describe a study, it means a prospective study, it will not be just an English word, it means a special study design.

Please be informed that there will be several lectures discussing the types of designs of medical studies in Module #2 of this course.

Dr. Moustafa

Please let me know if my answers for the 2 questions were clear or not.

Dr. Moustafa

I want to know the impression regarding the third lecture. Was it clear, because I have not received any comments or questions from the participants.

Yes sir

Honestly speaking, I was a bit confused between type 1 and type 2 errors . But I repeated the lecture around 3 times till I got it so far.

Now I am ok.

Thanks Dr Shokeir for your keen follow up

Dr. Moustafa

I am happy that it is clear now.

You are most welcome.

Yes Dr Shokier

Now so clear

Thank you very much

Dr Moustafa

It is perfect. I am so happy by your contribution and your persistence.

I am ready to answer your questions, read your comments, and know your impression. Please go in and share discussion.