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Yakvenalex [24]
3 years ago
12

Africa had several advanced civilizations during the Middle Ages

Social Studies
1 answer:
RideAnS [48]3 years ago
3 0
Yes the they did they had many ways that they used machienery like we do today

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What weakness did delegates at the Constitutional Convention see in the Articles of Confederation? A. The federal government cou
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This famous photograph taken by the voyager spacecraft shows _________.
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How to put survival in study when subjects are added in 10 months period?
Evgen [1.6K]
Learning Objectives

After completing this module, the student will be able to:

<span>Identify applications with time to event outcomesConstruct a life table using the actuarial approachConstruct a life table using the Kaplan-Meier approachPerform and interpret the log rank testCompute and interpret a hazard ratioInterpret coefficients in Cox proportional hazards regression analysis</span>

Time to Event Variables

There are unique features of time to event variables. First, times to event are always positive and their distributions are often skewed. For example, in a study assessing time to relapse in high risk patients, the majority of events (relapses) may occur early in the follow up with very few occurring later. On the other hand, in a study of time to death in a community based sample, the majority of events (deaths) may occur later in the follow up. Standard statistical procedures that assume normality of distributions do not apply. Nonparametric procedures could be invoked except for the fact that there are additional issues. Specifically, complete data (actual time to event data) is not always available on each participant in a study. In many studies, participants are enrolled over a period of time (months or years) and the study ends on a specific calendar date. Thus, participants who enroll later are followed for a shorter period than participants who enroll early. Some participants may drop out of the study before the end of the follow-up period (e.g., move away, become disinterested) and others may die during the follow-up period (assuming the outcome of interest is not death).

In each of these instances, we have incomplete follow-up information. True survival time (sometimes called failure time) is not known because the study ends or because a participant drops out of the study before experiencing the event. What we know is that the participants survival time is greater than their last observed follow-up time. These times are called censored times.

Censoring

There are several different types of censoring. The most common is called right censoring and occurs when a participant does not have the event of interest during the study and thus their last observed follow-up time is less than their time to event. This can occur when a participant drops out before the study ends or when a participant is event free at the end of the observation period.

In the first instance, the participants observed time is less than the length of the follow-up and in the second, the participant's observed time is equal to the length of the follow-up period. These issues are illustrated in the following examples.

 

Example:

A small prospective study is run and follows ten participants for the development of myocardial infarction (MI, or heart attack) over a period of 10 years. Participants are recruited into the study over a period of two years and are followed for up to 10 years. The graphic below indicates when they enrolled and what subsequently happened to them during the observation period.

During the study period, three participants suffer myocardial infarction (MI), one dies, two drop out of the study (for unknown reasons), and four complete the 10-year follow-up without suffering MI. The figure below shows the same data, but shows survival time starting at a common time zero (i.e., as if all participants enrolled in the study at the same time).


8 0
3 years ago
Who are the characters in the song "revolutionary tea" ? Who do they represent (symbolize) ?
tatiyna
Listen to the song then write down the names of the characters on a piece of paper then either look up what they symbolize or listen to the song again and see what they did
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Colt1911 [192]

Answer:

B) ignored the need for reform since there was relative economic affluence.

Explanation:

<u><em>For the United States, the post-World War II period was a time of prosperity. </em></u>The Americans used the money they had saved during World War II to purchase consumer goods that were not available during the conflict. With the subsequent boom in the economy, thousands of people found jobs in the United States. The Americans were making more money and the nation had the highest standard of living in the world. <u><em>Because of that, there was no reason to think about social reforms, once according to them, everything was just fine.</em></u>

6 0
2 years ago
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