Other
BIOSTATISTICS EXAM 1 (CHAP 1-15) STUDY GUIDE
- Course
- Institution
BIOSTATISTICS EXAM 1 (CHAP 1-15) STUDY GUIDE
[Show more]
Seller
Follow
GEEKA
Reviews received
Content preview
BIOSTATISTICS EXAM 1 (CHAP 1-15) STUDY GUIDEVariable - Answers- A characteristic that differs or varies between individuals.
Any experimental unit of observation for study.
Variability - Answers- The extent to which measurements/individuals/data points differ.
Variable Types - Answers- Numeric/continuous
Categorical
Variable Types: Numeric/Continuous - Answers- can be any numeric/quantitative value.
e.g. Age (can be made categorical), height, weight, mass, volume.
Variable Type Categorical - Answers- Finite or specific number of categories
e.g. gender: M or F
Why is there variability? (E.g. for strawberries) - Answers- -genetics
-nutrients
-sun exposure
-predators
-chance
-location
Statistical Tests - Answers- Test hypothesis.
Look for effects in the face of variability.
-Inferential statistics (Inferential= drawing conclusions on making inferences about
population based on data from a sample.)
Population - Answers- all individuals you are interested in studying
Sample - Answers- Subset of the population that we actually study.
We can use the sample to estimate the population. There will be the same error in our
estimate.
Example: What is the BMI (Body mass index) of adults in the United States?
Numeric: BMI= kg/m^2 or lb/in^2.
Categorical: Underweight <18.5
Healthy weight: 18.5-24.9
Overweight: 25.0-29.9
Obese>=30
,What would be our population? Why is it not feasible to study? - Answers- Our
population is all the adults in the United States.
It's not feasible because our population is too large, the study is too expensive, too time-
consuming, we would need to take into mind consent (can't force participation), and
usually hard to identify population.
Random Sample - Answers- Ideal sample where everybody in the population has an
equal probability of being chosen. Low bias in selecting the sample.
Method for Random Sample: (Adults in the United States) - Answers- 1) Define
inclusion and exclusion criteria to define population.
2) Determine sample size, n, and population size, N.
(generally the larger the sample size, the better it is)
3) # each of the individuals in the population
4) Use random number table or spss to determine the sample
Advantages of Random Sample - Answers- 1) Low bias, objective in selecting
individuals
2) Could potentially select from earlier population
3) Should be representative of population (in theory/has similar characteristics to the
population).
Disadvantages of a Random Sample - Answers- 1) May not be representative of the
population if n is small
2) Consent
3) Usually can't identify the entire population
Convenient Samples - Answers- Most typical sample in biology. We study individuals
that are convenient to study.
Convenient Samples Advantages - Answers- 1) Convenient
2) Mitigates costs and time consumption
=> make larger, add characteristics of population,
use previous experience and studies as a guide
Convenient Samples Disadvantages - Answers- 1) Not representative
2) Biased (by nature)
3) Volunteer bias: (if human volunteers: could be very different in unknown ways to
those that do not volunteer)
Descriptive statistics - Answers- Numbers that are used to describe or summarize the
data.
Two Classes:
1) Measure of Central tendency or Location
, 2) Measure of Variability or Dispersion
We can also evaluate sampling error (accuracy), standard error, confidence limits
(intervals)
Inferential Statistics - Answers- Statistical tests used to test hypotheses.
Gives us a snapshot of what our data set is like.
Measures of Central Tendency or Location - Answers- Mean, Median, Mode
Measures of Variability or Dispersion - Answers- Variance, Range, Standard Deviation
Descriptive Statistics E.g. Adults in the United States BMI
Random sample of n=110, adult males in the U.S.
Random sample of adult males in the U.S. n=9 - Answers- We would look at the
frequency on the y=axis, and BMI on the x-axis.
X-axis: Measured variable
Y-axis: Frequency/Count
Histogram - Answers- A graph of vertical bars representing the frequency distribution of
a set of data.
AKA Frequency graph/distribution
Mean - Answers- the arithmetic average of a distribution, obtained by adding the scores
and then dividing by the number of scores
y (bar)= Sum of y/ n
y= data point
n=sample size
Population Mean: miu=sum of y/N (population size)
-Most commonly reported measure of central tendency.
Median - Answers- middle value of an ordered data set
-arrange data in ascending order.
-use this formula to determine which value is the median
y_(n+1) * 0.5
Mode - Answers- the most frequently occurring score(s) in a distribution
Types of Distributions - Answers- Normal, Negatively skewed, Positively skewed
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller GEEKA. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for CA$18.75. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
75323 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now