Question

Causal Hypotheses

Find an example (or a summary) of a randomized experiment, controlled experiment, prospective observational study, or retrospective observational study. Good sources are news items about such studies.

Briefly describe the study, and in your account, identify the causal hypothesis the study has claimed to have supported as likely true, as well as the comparison groups.

Then think critically about the study: state what you think are possible uncontrolled confounding variables that, if true, could call into question the conclusion of the study.

Answer 1

Randomized experiment

In secience, randomized experiment allow greatest realiblity and validity in statistical estimate of treatment effect.randomization involving randomly allocated the experimental unit across the treatment group .

For example, if an experiment compared new drug against a standard drug , then patient should allocated to either a new drug or to the standard drug to controll randomization.

controlled experiment ,

In Controll experiment, the study of population often devided.

One group , recieve a change certain vriable and other group recieve certain standard Environment and conditions. This group reffred as control group and allows for comparison with other group is called experimental group .for example , to understand the impact of new drug on patient of diabetes two groups are constructed. In controll group provide normal medicine wheather experimental group provide new drug

. After certain period generalized that new drug has more effective for eliminate diseases as compare existing or normal drug.

prospective observational study

This study is generally conducted to understand the outcome of study . The study generally usually cohort of subject and watching them over a long period . Prospective study fewer potential source of biasness and confounding compare than retrospective study.

step 2

a hypothesis is statement that predicts the relationship between set of varisbles. casual hypothesis is is imply to predict cause and effect relationship.casual hypothesis aims to detrmine if change one variable then causes change to another variable.

uncontrolled confounding variable

a controlled variable is extra variable . This can ruin the experiment and give useless result . It is also increases bias in expeirment.in some cases confounding variable are not controlled this is called uncontrolled confounding variable .for example , a resercher can not controlled the confounding variable of age , sex etc