Statistics fall review

Front

What is the purpose of using a placebo in experiments?

Back

A placebo is used to control for the psychological effects of thinking one is receiving treatment, which can influence outcomes.

Front

What does a correlation coefficient of r = 0.89 indicate about the relationship between two variables?

Back

It indicates a strong positive correlation, meaning taller than average fathers tend to have taller than average sons.

Front

How do you determine the median from a frequency table?

Back

To find the median, locate the interval that contains the middle value when the data is ordered. In this case, the median grade is in the 71–80 interval.

Front

What is the main advantage of experiments over observational studies?

Back

Experiments can provide better evidence of causation due to controlled conditions.

Front

If 42% of voters are Democrats and 53% are Republicans, what is the probability of selecting a voter from another party?

Back

The probability is 0.05, calculated as 1 - (0.42 + 0.53).

Front

Define 'causation' in the context of statistics.

Back

Causation refers to a relationship where one event directly affects another event.

Front

What is the difference between descriptive and inferential statistics?

Back

Descriptive statistics summarize data, while inferential statistics make predictions or inferences about a population based on a sample.

Front

What is a confounding variable?

Back

A confounding variable is an outside influence that affects the dependent and independent variables, potentially skewing results.

Front

Explain the concept of 'random sampling'.

Back

Random sampling is a technique where each member of a population has an equal chance of being selected, ensuring a representative sample.

Front

What is the significance of a p-value in hypothesis testing?

Back

A p-value indicates the probability of obtaining the observed results if the null hypothesis is true; a low p-value suggests rejecting the null hypothesis.