Biostats Midterm Review

What is the general trend in statistics?

using information we gather from a sample to make inferences and conclusions about occurrences in a population

A ____ ___ is chosen by the investigator to remain at a set level of treatment

independent variable

A ___ ____ is one which we measure and record in an experimental or observational study

dependent variable

A ___ ___ is one which affects circumstances beyond the investigator’s control

confounding variable

H₁ is proper statistical notation for?

alternate hypothesis

H₀ is proper statistical nomination for?

null hypothesis

What does a null hypothesis imply or stress?

no difference

Which term is defined as a “whole entire group”?

population

In order for something to be scientifically tested, using either the scientific or statistical method, it must be:

well-defined

testable

measurable

controllable

What is an example of a type of Nominal data?

true/false

What is an example of Ordinal data?

warm/hot/hottest

What is an example of Ratio data?

volume in liters

If given a sum of squares, what must be done in order to calculate Variance?

divide by degrees of freedom

How is Sum of Squares calculated?

subtract each value from the mean, square each difference, and then add all of the differences together

How is Degrees of Freedom calculated?

subtract one from the number of observations

What P-value would a percent-probability of 25% be assigned?

P = 0.25

Given the P-value of P = 0.65, what percent does this represent?

65%

By convention, how many standard deviations away from the mean must an observation be in order to be considered an unlikely event?

more than 2 standard deviations

By convention, an observation must have a P-value less than this in order to be considered an unlikely event

P < 0.05

What can be done if one’s data is clearly not normally distributed?

transformation techniques

consult a professional statistician

randomly group observations and compare means

What is a characteristic of a normal distribution?

frequency of occurrence centered about the mean

What percentage of a normally-distributed population falls within 1 or more standard deviations of the mean?

68%

An observation with a P > 0.06 and P < 0.50 is statistically likely to occur or unlikely?

statistically likely

Is a normal distribution symmetrical?

yes

What percentage of a normally-distributed population falls within 2 or more standard deviations of the mean?

95%

In human genetics, sex is attributed to the presence of an X and/or Y chromosome. Human procreation requires the input of genetic material from one male (genotype: XY) and one female (genotype: XX); upon hypothetical crossing in a Punnett Square, they yield equal numbers of each gender. What is the P-value of achieving a female offspring?...and male offspring?

Female P = 0.5, Male P = 0.5

By convention, how many standard deviations away from the mean must an observation be in order to be considered an unlikely event?

2 or more standard deviations from the mean

An observation with a P > 0.06 and P < 0.50 is statistically likely to occur or unlikely?

Statistically likely

By convention, an observation must have a P-value less than this in order to be considered an unlikely event

P < 0.05

By convention, how many standard deviations away from the mean must an observation be in order to be considered an unlikely event?

2 or more standard deviations from the mean

An observation with a P>0.06 and P<0.50 is statistically likely to occur or unlikely?

statistically likely

By convention, an observation must have a P-value less than this in order to be considered an unlikely event.

P < 0.05

Is F < 1 significant or insignificant

Insignificant

Is F > 1 significant or insignificant

cannot determine, more info needed

What does “LSD” represent?

Least Significant difference

What are the phases of a basic ANOVA?

preparatory phase

phase one

phase two

end phase

As principle investigator of a neonatal medicine study, you are tasked with examining the possible link between low birth weights, and proximity to a coal fired power plant. The plant lies on the very western edge of the town of Statsburg, and it is hypothesized that a gradient effect may occur, radiating away from the plant. Which type of experimental design is most prudent?

randomized block experiment

You are investigating three types of Cannabis sativa for growth potential, measured in grams of leaf produced per variety. As this is illegal in the United States of America, your study area is rather remote. It is composed of a plot of cultivated land. You are tasked with examining the possibility of one plant growing a better yield than the others. It should be noted that Mr. Nolan's law enforcement friends may destroy part of your crop, if it is found. Which type of experimental design is most prudent in this scenario?

Fully randomized design

As a soil conservationist, you are investigating the seasonal levels of three species of nitrogen-fixing soil bacteria in the soils of the Indiana plains. Mr. Dann cautions you, "now, you have to account for the loessial (wind-blown) deposition; but be warned, it can change direction." Therefore, as lead investigator, which experimental design motif would you use to account for an unknown directional component?

Latin square design

By convention, how many standard deviations away from the mean must an observation be in order to be considered an unlikely event?

2 or more standard deviations from the mean

An observation with a P > 0.06 and P < 0.50 is statistically likely to occur or unlikely?

statistically likely

By convention, an observation must have a P-value less than this in order to be considered an unlikely event.

P < 0.05

What is a characteristic of a normal distribution?

frequency of occurrence centered about the mean